Turning down the noise: the benefit of musical training on the aging auditory brain

Speech-in-noise, psychosocial, and heart rate variability outcomes of group singing or audiobook club interventions for older adults with unaddressed hearing loss: A SingWell Project multisite, randomized controlled trial, registered report protocol

BACKGROUND

Unaddressed age-related hearing loss is highly prevalent among older adults, typified by negative consequences for speech-in-noise perception and psychosocial wellbeing. There is promising evidence that group singing may enhance speech-in-noise perception and psychosocial wellbeing. However, there is a lack of robust evidence, primarily due to the literature being based on small sample sizes, single site studies, and a lack of randomized controlled trials. Hence, to address these concerns, this SingWell Project study utilizes an appropriately powered sample size, multisite, randomized controlled trial approach, with a robust preplanned statistical analysis.

OBJECTIVE

To explore if group singing may improve speech-in-noise perception and psychosocial wellbeing for older adults with unaddressed hearing loss.

METHODS

We designed an international, multisite, randomized controlled trial to explore the benefits of group singing for adults aged 60 years and older with unaddressed hearing loss (registered at clinicaltrials.gov, ID: NCT06580847). After undergoing an eligibility screening process and completing an information and consent form, we intend to recruit 210 participants that will be randomly assigned to either group singing or an audiobook club (control group) intervention for a training period of 12-weeks. The study has multiple timepoints for testing, that are broadly categorized as macro (i.e., pre- and post-measures across the 12-weeks), or micro timepoints (i.e., pre- and post-measures across a weekly training session). Macro measures include behavioural measures of speech and music perception, and psychosocial questionnaires. Micro measures include psychosocial questionnaires and heart-rate variability.

HYPOTHESES

We hypothesize that group singing may be effective at improving speech perception and psychosocial outcomes for adults aged 60 years and older with unaddressed hearing loss-more so than participants in the control group.

Compensation or Preservation? Different Roles of Functional Lateralization in Speech Perception of Older Non-musicians and Musicians

Musical training can counteract age-related decline in speech perception in noisy environments. However, it remains unclear whether older non-musicians and musicians rely on functional compensation or functional preservation to counteract the adverse effects of aging. This study utilized resting-state functional connectivity (FC) to investigate functional lateralization, a fundamental organization feature, in older musicians (OM), older non-musicians (ONM), and young non-musicians (YNM). Results showed that OM outperformed ONM and achieved comparable performance to YNM in speech-in-noise and speech-in-speech tasks. ONM exhibited reduced lateralization than YNM in lateralization index (LI) of intrahemispheric FC (LI_intra) in the cingulo-opercular network (CON) and LI of interhemispheric heterotopic FC (LI_he) in the language network (LAN). Conversely, OM showed higher neural alignment to YNM (i.e., a more similar lateralization pattern) compared to ONM in CON, LAN, frontoparietal network (FPN), dorsal attention network (DAN), and default mode network (DMN), indicating preservation of youth-like lateralization patterns due to musical experience. Furthermore, in ONM, stronger left-lateralized and lower alignment-to-young of LI_intra in the somatomotor network (SMN) and DAN and LI_he in DMN correlated with better speech performance, indicating a functional compensation mechanism. In contrast, stronger right-lateralized LI_intra in FPN and DAN and higher alignment-to-young of LI_he in LAN correlated with better performance in OM, suggesting a functional preservation mechanism. These findings highlight the differential roles of functional preservation and compensation of lateralization in speech perception in noise among elderly individuals with and without musical expertise, offering insights into successful aging theories from the lens of functional lateralization and speech perception.

Attention, working memory, and inhibitory control in aging: Comparing amateur singers, instrumentalists, and active controls

Despite the ubiquity of musical activities, little is known about the specificity of their association with executive functions. In this cross-sectional study, we examined this relationship as a function of age. Our main hypotheses were that executive functions would decline in older age, that this relationship would be reduced in singers and instrumentalists compared to nonmusician active controls, and that the amount of musical experience would be more strongly associated with executive functions compared to the specific type of activity. A sample of 122 cognitively healthy adults aged 20-88 years was recruited, consisting of 39 amateur singers, 43 amateur instrumentalists, and 40 nonmusician controls. Tests of auditory processing speed, auditory selective attention, auditory and visual inhibitory control, and auditory working memory were administered. The results confirm a negative relationship between age and executive functions. While musicians' advantages were found in selective attention, inhibitory control, and auditory working memory, these advantages were specific rather than global. Furthermore, most of these advantages were independent of age and experience. Finally, there were only limited differences between instrumentalists and singers, suggesting that the relationship between music-making activities and executive functions may be, at least in part, general as opposed to activity-specific.

Musicianship Modulates Cortical Effects of Attention on Processing Musical Triads

Background: Many studies have demonstrated the benefits of long-term music training (i.e., musicianship) on the neural processing of sound, including simple tones and speech. However, the effects of musicianship on the encoding of simultaneously presented pitches, in the form of complex musical chords, is less well established. Presumably, musicians' stronger familiarity and active experience with tonal music might enhance harmonic pitch representations, perhaps in an attention-dependent manner. Additionally, attention might influence chordal encoding differently across the auditory system. To this end, we explored the effects of long-term music training and attention on the processing of musical chords at the brainstem and cortical levels. Method: Young adult participants were separated into musician and nonmusician groups based on the extent of formal music training. While recording EEG, listeners heard isolated musical triads that differed only in the chordal third: major, minor, and detuned (4% sharper third from major). Participants were asked to correctly identify chords via key press during active stimulus blocks and watched a silent movie during passive blocks. We logged behavioral identification accuracy and reaction times and calculated information transfer based on the behavioral chord confusion patterns. EEG data were analyzed separately to distinguish between cortical (event-related potential, ERP) and subcortical (frequency-following response, FFR) evoked responses. Results: We found musicians were (expectedly) more accurate, though not faster, than nonmusicians in chordal identification. For subcortical FFRs, responses showed stimulus chord effects but no group differences. However, for cortical ERPs, whereas musicians displayed P2 (~150 ms) responses that were invariant to attention, nonmusicians displayed reduced P2 during passive listening. Listeners' degree of behavioral information transfer (i.e., success in distinguishing chords) was also better in musicians and correlated with their neural differentiation of chords in the ERPs (but not high-frequency FFRs). Conclusions: Our preliminary results suggest long-term music training strengthens even the passive cortical processing of musical sounds, supporting more automated brain processing of musical chords with less reliance on attention. Our results also suggest that the degree to which listeners can behaviorally distinguish chordal triads is directly related to their neural specificity to musical sounds primarily at cortical rather than subcortical levels. FFR attention effects were likely not observed due to the use of high-frequency stimuli (>220 Hz), which restrict FFRs to brainstem sources.

Network connectivity differences in music listening among older adults following a music-based intervention

Music-based interventions are a common feature in long-term care with clinical reports highlighting music's ability to engage individuals with complex diagnoses. While these findings are promising, normative findings from healthy controls are needed to disambiguate treatment effects unique to pathology and those seen in healthy aging. The present study examines brain network dynamics during music listening in a sample of healthy older adults before and after a music-based intervention. We found intervention effects from hidden Markov model-estimated fMRI network data. Following the intervention, participants demonstrated greater occupancy (the amount of time a network was occupied) in a temporal-mesolimbic network. We conclude that network dynamics in healthy older adults are sensitive to music-based interventions. We discuss these findings' implications for future studies with individuals with neurodegeneration.

Effects of Memantine on the Auditory Steady-State and Harmonic Responses to 40 Hz Stimulation Across Species

BACKGROUND

Click trains elicit an auditory steady-state response (ASSR) at the driving frequency (1F) and its integer multiple frequencies (2F, 3F, etc.) called harmonics; we call this harmonic response the steady-state harmonic response (SSHR). We describe the 40 Hz ASSR (1F) and 80 Hz SSHR (2F) in humans and rats and their sensitivity to the uncompetitive NMDA antagonist memantine.

METHODS

In humans (healthy control participants, n = 25; patients with schizophrenia, n = 28), electroencephalography was recorded after placebo or 20 mg memantine in a within-participant crossover design. ASSR used 1 ms, 85-dB clicks presented in 250 40/s 500-ms trains. In freely moving rats (n = 9), electroencephalography was acquired after memantine (0, 0.3, 1, 3 mg/kg) in a within-participant crossover design; 65-dB click trains used 5-mV monophasic, 1-ms square waves (40/s).

RESULTS

Across species, ASSR at 1F generated greater evoked power (EP) than the 2F SSHR. 1F > 2F intertrial coherence (ITC) was also detected in humans, but the opposite relationship (ITC: 2F > 1F) was seen in rats. EP and ITC at 1F were deficient in patients and were enhanced by memantine across species. EP and ITC at 2F were deficient in patients. Measures at 2F were generally insensitive to memantine across species, although in humans the ITC harmonic ratio (1F:2F) was modestly enhanced by memantine, and in rats, both the EP and ITC harmonic ratios were significantly enhanced by memantine.

CONCLUSIONS

ASSR and SSHR are robust, nonredundant electroencephalography signals that are suitable for cross-species analyses that reveal potentially meaningful differences across species, diagnoses, and drugs.

Generalization of auditory expertise in audio engineers and instrumental musicians

From auditory perception to general cognition, the ability to play a musical instrument has been associated with skills both related and unrelated to music. However, it is unclear if these effects are bound to the specific characteristics of musical instrument training, as little attention has been paid to other populations such as audio engineers and designers whose auditory expertise may match or surpass that of musicians in specific auditory tasks or more naturalistic acoustic scenarios. We explored this possibility by comparing students of audio engineering (n = 20) to matched conservatory-trained instrumentalists (n = 24) and to naive controls (n = 20) on measures of auditory discrimination, auditory scene analysis, and speech in noise perception. We found that audio engineers and performing musicians had generally lower psychophysical thresholds than controls, with pitch perception showing the largest effect size. Compared to controls, audio engineers could better memorise and recall auditory scenes composed of non-musical sounds, whereas instrumental musicians performed best in a sustained selective attention task with two competing streams of tones. Finally, in a diotic speech-in-babble task, musicians showed lower signal-to-noise-ratio thresholds than both controls and engineers; however, a follow-up online study did not replicate this musician advantage. We also observed differences in personality that might account for group-based self-selection biases. Overall, we showed that investigating a wider range of forms of auditory expertise can help us corroborate (or challenge) the specificity of the advantages previously associated with musical instrument training.

Heightened OAEs in young adult musicians: Influence of current noise exposure and training recency

Otoacoustic emissions (OAEs) are a non-invasive metric of cochlear function. Studies of OAEs in musicians have yielded mixed results, ranging from evidence of diminished OAEs in musicians-suggesting noise-induced hearing loss-to no difference when compared to non-musicians, or even a trend for stronger OAEs in musicians. The goal of this study was to use a large sample of college students with normal hearing (n = 160) to compare OAE SNRs in musicians and non-musicians and to explore potential effects of training recency and noise exposure on OAEs in these cohorts. The musician cohort included both active musicians (who at the time of enrollment practiced at least weekly) and past musicians (who had at least 6 years of training). All participants completed a questionnaire about recent noise exposure (previous 12 months), and a subset of participants (71 musicians and 15 non-musicians) wore a personal noise dosimeter for one week to obtain a more nuanced and objective measure of exposure to assess how different exposure levels may affect OAEs before the emergence of a clinically significant hearing loss. OAEs were tested using both transient-evoked OAEs (TEOAEs) and distortion-product OAEs (DPOAEs). As predicted from the literature, musicians experienced significantly higher noise levels than non-musicians based on both subjective (self-reported) and objective measures. Yet we found stronger TEOAEs and DPOAEs in musicians compared to non-musicians in the ∼1-5 kHz range. Comparisons between past and active musicians suggest that enhanced cochlear function in young adult musicians does not require active, ongoing musical practice. Although there were no significant relations between OAEs and noise exposure as measured by dosimetry or questionnaire, active musicians had weaker DPOAEs than past musicians when the entire DPOAE frequency range was considered (up to ∼16 kHz), consistent with a subclinical noise-induced hearing loss that only becomes apparent when active musicians are contrasted with a cohort of individuals with comparable training but without the ongoing risks of noise exposure. Our findings suggest, therefore, that separate norms should be developed for musicians for earlier detection of incipient hearing loss. Potential explanations for enhanced cochlear function in musicians include pre-existing (inborn or demographic) differences, training-related enhancements of cochlear function (e.g., upregulation of prestin, stronger efferent feedback mechanisms), or a combination thereof. Further studies are needed to determine if OAE enhancements offer musicians protection against damage caused by noise exposure.

Short- and long-term neuroplasticity interact during the perceptual learning of concurrent speech

Plasticity from auditory experience shapes the brain's encoding and perception of sound. However, whether such long-term plasticity alters the trajectory of short-term plasticity during speech processing has yet to be investigated. Here, we explored the neural mechanisms and interplay between short- and long-term neuroplasticity for rapid auditory perceptual learning of concurrent speech sounds in young, normal-hearing musicians and nonmusicians. Participants learned to identify double-vowel mixtures during ~ 45 min training sessions recorded simultaneously with high-density electroencephalography (EEG). We analyzed frequency-following responses (FFRs) and event-related potentials (ERPs) to investigate neural correlates of learning at subcortical and cortical levels, respectively. Although both groups showed rapid perceptual learning, musicians showed faster behavioral decisions than nonmusicians overall. Learning-related changes were not apparent in brainstem FFRs. However, plasticity was highly evident in cortex, where ERPs revealed unique hemispheric asymmetries between groups suggestive of different neural strategies (musicians: right hemisphere bias; nonmusicians: left hemisphere). Source reconstruction and the early (150-200 ms) time course of these effects localized learning-induced cortical plasticity to auditory-sensory brain areas. Our findings reinforce the domain-general benefits of musicianship but reveal that successful speech sound learning is driven by a critical interplay between long- and short-term mechanisms of auditory plasticity, which first emerge at a cortical level.

Fractal Phototherapy in Maximizing Retina and Brain Plasticity

The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.

Temporal deployment of attention in musicians: Evidence from an attentional blink paradigm

The generalization of music training to unrelated nonmusical domains is well established and may reflect musicians' superior ability to regulate attention. We investigated the temporal deployment of attention in musicians and nonmusicians using scalp-recording of event-related potentials in an attentional blink (AB) paradigm. Participants listened to rapid sequences of stimuli and identified target and probe sounds. The AB was defined as a probe identification deficit when the probe closely follows the target. The sequence of stimuli was preceded by a neutral or informative cue about the probe position within the sequence. Musicians outperformed nonmusicians in identifying the target and probe. In both groups, cueing improved target and probe identification and reduced the AB. The informative cue elicited a sustained potential, which was more prominent in musicians than nonmusicians over left temporal areas and yielded a larger N1 amplitude elicited by the target. The N1 was larger in musicians than nonmusicians, and its amplitude over the left frontocentral cortex of musicians correlated with accuracy. Together, these results reveal musicians' superior ability to regulate attention, allowing them to prepare for incoming stimuli, thereby improving sound object identification. This capacity to manage attentional resources to optimize task performance may generalize to nonmusical activities.

Speech Production in Healthy Older Adults With or Without Amateur Singing Experience

PURPOSE

Amateur singing is a universal, accessible, and enjoyable musical activity that may have positive impacts on human communication. However, evidence of an impact of singing on speech articulation is still scarce, yet understanding the effects of vocal training on speech production could provide a model for treating people with speech deficits. The aim of this study was to examine speech production in younger and older adults with or without amateur singing experience.

METHOD

Thirty-eight amateur singers (aged 20-87 years, 23 women and 15 men) and 40 nonmusician active controls (aged 23-88 years, 19 women and 21 men) were recruited. A set of tasks were used to evaluate the oral motor sphere: two voice production tasks, a passage reading task, and a modified diadochokinetic (DDK) rates task performed at a natural rhythm and as quickly as possible.

RESULTS

Our results show that older age was associated with lower reading rate, lower articulation rate, and articulation rate variability in the DDK task, as well as reduced accuracy for the phonologically complex stimuli. Most importantly, our results show an advantage for singers over cognitively active nonsingers in terms of articulatory accuracy in the most challenging situations.

CONCLUSION

This result suggests extended maximal performance capacities in amateur singers perhaps resulting from the articulatory efforts required during singing.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24274813.

Functional Organization of Auditory and Reward Systems in Aging

The intrinsic organization of functional brain networks is known to change with age, and is affected by perceptual input and task conditions. Here, we compare functional activity and connectivity during music listening and rest between younger (n = 24) and older (n = 24) adults, using whole-brain regression, seed-based connectivity, and ROI-ROI connectivity analyses. As expected, activity and connectivity of auditory and reward networks scaled with liking during music listening in both groups. Younger adults show higher within-network connectivity of auditory and reward regions as compared with older adults, both at rest and during music listening, but this age-related difference at rest was reduced during music listening, especially in individuals who self-report high musical reward. Furthermore, younger adults showed higher functional connectivity between auditory network and medial prefrontal cortex that was specific to music listening, whereas older adults showed a more globally diffuse pattern of connectivity, including higher connectivity between auditory regions and bilateral lingual and inferior frontal gyri. Finally, connectivity between auditory and reward regions was higher when listening to music selected by the participant. These results highlight the roles of aging and reward sensitivity on auditory and reward networks. Results may inform the design of music-based interventions for older adults and improve our understanding of functional network dynamics of the brain at rest and during a cognitively engaging task.

Short- and long-term experience-dependent neuroplasticity interact during the perceptual learning of concurrent speech

Plasticity from auditory experiences shapes brain encoding and perception of sound. However, whether such long-term plasticity alters the trajectory of short-term plasticity during speech processing has yet to be investigated. Here, we explored the neural mechanisms and interplay between short- and long-term neuroplasticity for rapid auditory perceptual learning of concurrent speech sounds in young, normal-hearing musicians and nonmusicians. Participants learned to identify double-vowel mixtures during ∼45 minute training sessions recorded simultaneously with high-density EEG. We analyzed frequency-following responses (FFRs) and event-related potentials (ERPs) to investigate neural correlates of learning at subcortical and cortical levels, respectively. While both groups showed rapid perceptual learning, musicians showed faster behavioral decisions than nonmusicians overall. Learning-related changes were not apparent in brainstem FFRs. However, plasticity was highly evident in cortex, where ERPs revealed unique hemispheric asymmetries between groups suggestive of different neural strategies (musicians: right hemisphere bias; nonmusicians: left hemisphere). Source reconstruction and the early (150-200 ms) time course of these effects localized learning-induced cortical plasticity to auditory-sensory brain areas. Our findings confirm domain-general benefits for musicianship but reveal successful speech sound learning is driven by a critical interplay between long- and short-term mechanisms of auditory plasticity that first emerge at a cortical level.

No Musician Advantage in the Perception of Degraded-Fundamental Frequency Speech in Noisy Environments

PURPOSE

Pitch variations of the fundamental frequency (f_o) contour contribute to speech perception in noisy environments, but whether musicians confer an advantage in speech in noise (SIN) with altered f_o information remains unclear. This study investigated the effects of different levels of degraded f_o contour (i.e., conveying lexical tone or intonation information) on musician advantage in speech-in-noise perception.

METHOD

A cohort of native Mandarin Chinese speakers, comprising 30 trained musicians and 30 nonmusicians, were tested on the intelligibility of Mandarin Chinese sentences with natural, flattened-tone, flattened-intonation, and flattened-all f_o contours embedded in background noise masked under three signal-to-noise ratios (0, -5, and -9 dB). Pitch difference thresholds and innate musical skills associated with speech-in-noise benefits were also assessed.

RESULTS

Speech intelligibility score improved with increasing signal-to-noise level for both musicians and nonmusicians. However, no musician advantage was observed for identifying any type of flattened-f_o contour SIN. Musicians exhibited smaller f_o pitch discrimination limens than nonmusicians, which correlated with benefits for perceiving speech with intact tone-level f_o information. Regardless of musician status, performance on the pitch and accent musical-skill subtests correlated with speech intelligibility score.

CONCLUSIONS

Collectively, these results provide no evidence for a musician advantage for perceiving speech with distorted f_o information in noisy environments. Results further show that perceptual musical skills on pitch and accent processing may benefit the perception of SIN, independent of formal musical training. Our findings suggest that the potential application of music training in speech perception in noisy backgrounds is not contingent on the ability to process f_o pitch contours, at least for Mandarin Chinese speakers.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23706354.

Successful aging of musicians: Preservation of sensorimotor regions aids audiovisual speech-in-noise perception

Musicianship can mitigate age-related declines in audiovisual speech-in-noise perception. We tested whether this benefit originates from functional preservation or functional compensation by comparing fMRI responses of older musicians, older nonmusicians, and young nonmusicians identifying noise-masked audiovisual syllables. Older musicians outperformed older nonmusicians and showed comparable performance to young nonmusicians. Notably, older musicians retained similar neural specificity of speech representations in sensorimotor areas to young nonmusicians, while older nonmusicians showed degraded neural representations. In the same region, older musicians showed higher neural alignment to young nonmusicians than older nonmusicians, which was associated with their training intensity. In older nonmusicians, the degree of neural alignment predicted better performance. In addition, older musicians showed greater activation in frontal-parietal, speech motor, and visual motion regions and greater deactivation in the angular gyrus than older nonmusicians, which predicted higher neural alignment in sensorimotor areas. Together, these findings suggest that musicianship-related benefit in audiovisual speech-in-noise processing is rooted in preserving youth-like representations in sensorimotor regions.

Age differences in central auditory system responses to naturalistic music

Aging influences the central auditory system leading to difficulties in the decoding and understanding of overlapping sound signals, such as speech in noise or polyphonic music. Studies on central auditory system evoked responses (ERs) have found in older compared to young listeners increased amplitudes (less inhibition) of the P1 and N1 and decreased amplitudes of the P2, mismatch negativity (MMN), and P3a responses. While preceding research has focused on simplified auditory stimuli, we here tested whether the previously observed age-related differences could be replicated with sounds embedded in medium and highly naturalistic musical contexts. Older (age 55-77 years) and younger adults (age 21-31 years) listened to medium naturalistic (synthesized melody) and highly naturalistic (studio recording of a music piece) stimuli. For the medium naturalistic music, the age group differences on the P1, N1, P2, MMN, and P3a amplitudes were all replicated. The age group differences, however, appeared reduced with the highly compared to the medium naturalistic music. The finding of lower P2 amplitude in older than young was replicated for slow event rates (0.3-2.9Hz) in the highly naturalistic music. Moreover, the ER latencies suggested a gradual slowing of the auditory processing time course for highly compared to medium naturalistic stimuli irrespective of age. These results support that age-related differences on ERs can partly be observed with naturalistic stimuli. This opens new avenues for including naturalistic stimuli in the investigation of age-related central auditory system disorders.

Adaptation in auditory processing

Adaptation is an essential feature of auditory neurons, which reduces their responses to unchanging and recurring sounds and allows their response properties to be matched to the constantly changing statistics of sounds that reach the ears. As a consequence, processing in the auditory system highlights novel or unpredictable sounds and produces an efficient representation of the vast range of sounds that animals can perceive by continually adjusting the sensitivity and, to a lesser extent, the tuning properties of neurons to the most commonly encountered stimulus values. Together with attentional modulation, adaptation to sound statistics also helps to generate neural representations of sound that are tolerant to background noise and therefore plays a vital role in auditory scene analysis. In this review, we consider the diverse forms of adaptation that are found in the auditory system in terms of the processing levels at which they arise, the underlying neural mechanisms, and their impact on neural coding and perception. We also ask what the dynamics of adaptation, which can occur over multiple timescales, reveal about the statistical properties of the environment. Finally, we examine how adaptation to sound statistics is influenced by learning and experience and changes as a result of aging and hearing loss.

Are musical activities associated with enhanced speech perception in noise in adults? A systematic review and meta-analysis

The ability to process speech in noise (SPiN) declines with age, with a detrimental impact on life quality. Music-making activities such as singing and playing a musical instrument have raised interest as potential prevention strategies for SPiN perception decline because of their positive impact on several brain system, especially the auditory system, which is critical for SPiN. However, the literature on the effect of musicianship on SPiN performance has yielded mixed results. By critically assessing the existing literature with a systematic review and a meta-analysis, we aim to provide a comprehensive portrait of the relationship between music-making activities and SPiN in different experimental conditions. 38/49 articles, most focusing on young adults, were included in the quantitative analysis. The results show a positive relationship between music-making activities and SPiN, with the strongest effects found in the most challenging listening conditions, and little to no effect in less challenging situations. This pattern of results supports the notion of a relative advantage for musicians on SPiN performance and clarify the scope of this effect. However, further studies, especially with older adults, using adequate randomization methods, are needed to extend the present conclusions and assess the potential for musical activities to be used to mitigate SPiN decline in seniors.

Continuous dynamics in behavior reveal interactions between perceptual warping in categorization and speech-in-noise perception

Introduction

Spoken language comprehension requires listeners map continuous features of the speech signal to discrete category labels. Categories are however malleable to surrounding context and stimulus precedence; listeners' percept can dynamically shift depending on the sequencing of adjacent stimuli resulting in a warping of the heard phonetic category. Here, we investigated whether such perceptual warping-which amplify categorical hearing-might alter speech processing in noise-degraded listening scenarios.

Methods

We measured continuous dynamics in perception and category judgments of an acoustic-phonetic vowel gradient via mouse tracking. Tokens were presented in serial vs. random orders to induce more/less perceptual warping while listeners categorized continua in clean and noise conditions.

Results

Listeners' responses were faster and their mouse trajectories closer to the ultimate behavioral selection (marked visually on the screen) in serial vs. random order, suggesting increased perceptual attraction to category exemplars. Interestingly, order effects emerged earlier and persisted later in the trial time course when categorizing speech in noise.

Discussion

These data describe interactions between perceptual warping in categorization and speech-in-noise perception: warping strengthens the behavioral attraction to relevant speech categories, making listeners more decisive (though not necessarily more accurate) in their decisions of both clean and noise-degraded speech.

Enduring musician advantage among former musicians in prosodic pitch perception

Musical training has been associated with various cognitive benefits, one of which is enhanced speech perception. However, most findings have been based on musicians taking part in ongoing music lessons and practice. This study thus sought to determine whether the musician advantage in pitch perception in the language domain extends to individuals who have ceased musical training and practice. To this end, adult active musicians (n = 22), former musicians (n = 27), and non-musicians (n = 47) were presented with sentences spoken in a native language, English, and a foreign language, French. The final words of the sentences were either prosodically congruous (spoken at normal pitch height), weakly incongruous (pitch was increased by 25%), or strongly incongruous (pitch was increased by 110%). Results of the pitch discrimination task revealed that although active musicians outperformed former musicians, former musicians outperformed non-musicians in the weakly incongruous condition. The findings suggest that the musician advantage in pitch perception in speech is retained to some extent even after musical training and practice is discontinued.

Auditory cognitive aging in amateur singers and non-singers

The notion that lifestyle factors, such as music-making activities, can affect cognitive functioning and reduce cognitive decline in aging is often referred to as the mental exercise hypothesis. One ubiquitous musical activity is choir singing. Like other musical activities, singing is hypothesized to impact cognitive and especially executive functions. Despite the commonness of choir singing, little is known about the extent to which singing can affect cognition in adulthood. In this cross-sectional group study, we examined the relationship between age and four auditory executive functions to test hypotheses about the relationship between the level of mental activity and cognitive functioning. We also examined pitch discrimination capabilities. A non-probabilistic sample of 147 cognitively healthy adults was recruited, which included 75 non-singers (mean age 52.5 ± 20.3; 20-98 years) and 72 singers (mean age 55.5 ± 19.2; 21-87 years). Tests of selective attention, processing speed, inhibitory control, and working memory were administered to all participants. Our main hypothesis was that executive functions and age would be negatively correlated, and that this relationship would be stronger in non-singers than singers, consistent with the differential preservation hypothesis. The alternative hypothesis - preserved differentiation - predicts that the difference between singers and non-singers in executive functions is unaffected by age. Our results reveal a detrimental effect of age on processing speed, selective attention, inhibitory control and working memory. The effect of singing was comparatively more limited, being positively associated only with frequency discrimination, processing speed, and, to some extent, inhibitory control. Evidence of differential preservation was limited to processing speed. We also found a circumscribed positive impact of age of onset and a negative impact of singing experience on cognitive functioning in singers. Together, these findings were interpreted as reflecting an age-related decline in executive function in cognitively healthy adults, with specific and limited positive impacts of singing, consistent with the preserved differentiation hypothesis, but not with the differential preservation hypothesis.

Neural Entrainment to Musical Pulse in Naturalistic Music Is Preserved in Aging: Implications for Music-Based Interventions

Neural entrainment to musical rhythm is thought to underlie the perception and production of music. In aging populations, the strength of neural entrainment to rhythm has been found to be attenuated, particularly during attentive listening to auditory streams. However, previous studies on neural entrainment to rhythm and aging have often employed artificial auditory rhythms or limited pieces of recorded, naturalistic music, failing to account for the diversity of rhythmic structures found in natural music. As part of larger project assessing a novel music-based intervention for healthy aging, we investigated neural entrainment to musical rhythms in the electroencephalogram (EEG) while participants listened to self-selected musical recordings across a sample of younger and older adults. We specifically measured neural entrainment to the level of musical pulse-quantified here as the phase-locking value (PLV)-after normalizing the PLVs to each musical recording's detected pulse frequency. As predicted, we observed strong neural phase-locking to musical pulse, and to the sub-harmonic and harmonic levels of musical meter. Overall, PLVs were not significantly different between older and younger adults. This preserved neural entrainment to musical pulse and rhythm could support the design of music-based interventions that aim to modulate endogenous brain activity via self-selected music for healthy cognitive aging.

Musical experience partially counteracts temporal speech processing deficits in putative mild cognitive impairment

Mild cognitive impairment (MCI) commonly results in more rapid cognitive and behavioral declines than typical aging. Individuals with MCI can exhibit impaired receptive speech abilities that may reflect neurophysiological changes in auditory-sensory processing prior to usual cognitive deficits. Benefits from current interventions targeting communication difficulties in MCI are limited. Yet, neuroplasticity associated with musical experience has been implicated in improving neural representations of speech and offsetting age-related declines in perception. Here, we asked whether these experience-dependent effects of musical experience might extend to aberrant aging and offer some degree of cognitive protection against MCI. During a vowel categorization task, we recorded single-channel electroencephalograms (EEGs) in older adults with putative MCI to evaluate speech encoding across subcortical and cortical levels of the auditory system. Critically, listeners varied in their duration of formal musical experience (0-21 years). Musical experience sharpened temporal precision in auditory cortical responses, suggesting that musical experience produces more efficient processing of acoustic features by counteracting age-related neural delays. Additionally, robustness of brainstem responses predicted the severity of cognitive decline, suggesting that early speech representations are sensitive to preclinical stages of cognitive impairment. Our results extend prior studies by demonstrating positive benefits of musical experience in older adults with emergent cognitive impairments.

Domain-specific hearing-in-noise performance is associated with absolute pitch proficiency

Recent evidence suggests that musicians may have an advantage over non-musicians in perceiving speech against noisy backgrounds. Previously, musicians have been compared as a homogenous group, despite demonstrated heterogeneity, which may contribute to discrepancies between studies. Here, we investigated whether “quasi”-absolute pitch (AP) proficiency, viewed as a general trait that varies across a spectrum, accounts for the musician advantage in hearing-in-noise (HIN) performance, irrespective of whether the streams are speech or musical sounds. A cohort of 12 non-musicians and 42 trained musicians stratified into high, medium, or low AP proficiency identified speech or melody targets masked in noise (speech-shaped, multi-talker, and multi-music) under four signal-to-noise ratios (0, − 3, − 6, and − 9 dB). Cognitive abilities associated with HIN benefits, including auditory working memory and use of visuo-spatial cues, were assessed. AP proficiency was verified against pitch adjustment and relative pitch tasks. We found a domain-specific effect on HIN perception: quasi-AP abilities were related to improved perception of melody but not speech targets in noise. The quasi-AP advantage extended to tonal working memory and the use of spatial cues, but only during melodic stream segregation. Overall, the results do not support the putative musician advantage in speech-in-noise perception, but suggest a quasi-AP advantage in perceiving music under noisy environments.

The effects of aging and musicianship on the use of auditory streaming cues

Auditory stream segregation, or separating sounds into their respective sources and tracking them over time, is a fundamental auditory ability. Previous research has separately explored the impacts of aging and musicianship on the ability to separate and follow auditory streams. The current study evaluated the simultaneous effects of age and musicianship on auditory streaming induced by three physical features: intensity, spectral envelope and temporal envelope. In the first study, older and younger musicians and non-musicians with normal hearing identified deviants in a four-note melody interleaved with distractors that were more or less similar to the melody in terms of intensity, spectral envelope and temporal envelope. In the second study, older and younger musicians and non-musicians participated in a dissimilarity rating paradigm with pairs of melodies that differed along the same three features. Results suggested that auditory streaming skills are maintained in older adults but that older adults rely on intensity more than younger adults while musicianship is associated with increased sensitivity to spectral and temporal envelope, acoustic features that are typically less effective for stream segregation, particularly in older adults.

Does music training enhance auditory and linguistic processing? A systematic review and meta-analysis of behavioral and brain evidence

It is often claimed that music training improves auditory and linguistic skills. Results of individual studies are mixed, however, and most evidence is correlational, precluding inferences of causation. Here, we evaluated data from 62 longitudinal studies that examined whether music training programs affect behavioral and brain measures of auditory and linguistic processing (N = 3928). For the behavioral data, a multivariate meta-analysis revealed a small positive effect of music training on both auditory and linguistic measures, regardless of the type of assignment (random vs. non-random), training (instrumental vs. non-instrumental), and control group (active vs. passive). The trim-and-fill method provided suggestive evidence of publication bias, but meta-regression methods (PET-PEESE) did not. For the brain data, a narrative synthesis also documented benefits of music training, namely for measures of auditory processing and for measures of speech and prosody processing. Thus, the available literature provides evidence that music training produces small neurobehavioral enhancements in auditory and linguistic processing, although future studies are needed to confirm that such enhancements are not due to publication bias.

Transcranial Direct Current Stimulation Combined With Listening to Preferred Music Alters Cortical Speech Processing in Older Adults

Emerging evidence suggests transcranial direct current stimulation (tDCS) can improve cognitive performance in older adults. Similarly, music listening may improve arousal and stimulate subsequent performance on memory-related tasks. We examined the synergistic effects of tDCS paired with music listening on auditory neurobehavioral measures to investigate causal evidence of short-term plasticity in speech processing among older adults. In a randomized sham-controlled crossover study, we measured how combined anodal tDCS over dorsolateral prefrontal cortex (DLPFC) paired with listening to autobiographically salient music alters neural speech processing in older adults compared to either music listening (sham stimulation) or tDCS alone. EEG assays included both frequency-following responses (FFRs) and auditory event-related potentials (ERPs) to trace neuromodulation-related changes at brainstem and cortical levels. Relative to music without tDCS (sham), we found tDCS alone (without music) modulates the early cortical neural encoding of speech in the time frame of ∼100-150 ms. Whereas tDCS by itself appeared to largely produce suppressive effects (i.e., reducing ERP amplitude), concurrent music with tDCS restored responses to those of the music+sham levels. However, the interpretation of this effect is somewhat ambiguous as this neural modulation could be attributable to a true effect of tDCS or presence/absence music. Still, the combined benefit of tDCS+music (above tDCS alone) was correlated with listeners' education level suggesting the benefit of neurostimulation paired with music might depend on listener demographics. tDCS changes in speech-FFRs were not observed with DLPFC stimulation. Improvements in working memory pre to post session were also associated with better speech-in-noise listening skills. Our findings provide new causal evidence that combined tDCS+music relative to tDCS-alone (i) modulates the early (100-150 ms) cortical encoding of speech and (ii) improves working memory, a cognitive skill which may indirectly bolster noise-degraded speech perception in older listeners.

Amateur singing benefits speech perception in aging under certain conditions of practice: behavioural and neurobiological mechanisms

Limited evidence has shown that practising musical activities in aging, such as choral singing, could lessen age-related speech perception in noise (SPiN) difficulties. However, the robustness and underlying mechanism of action of this phenomenon remain unclear. In this study, we used surface-based morphometry combined with a moderated mediation analytic approach to examine whether singing-related plasticity in auditory and dorsal speech stream regions is associated with better SPiN capabilities. 36 choral singers and 36 non-singers aged 20-87 years underwent cognitive, auditory, and SPiN assessments. Our results provide important new insights into experience-dependent plasticity by revealing that, under certain conditions of practice, amateur choral singing is associated with age-dependent structural plasticity within auditory and dorsal speech regions, which is associated with better SPiN performance in aging. Specifically, the conditions of practice that were associated with benefits on SPiN included frequent weekly practice at home, several hours of weekly group singing practice, singing in multiple languages, and having received formal singing training. These results suggest that amateur choral singing is associated with improved SPiN through a dual mechanism involving auditory processing and auditory-motor integration and may be dose dependent, with more intense singing associated with greater benefit. Our results, thus, reveal that the relationship between singing practice and SPiN is complex, and underscore the importance of considering singing practice behaviours in understanding the effects of musical activities on the brain-behaviour relationship.

The Impact of Music Training and Working Memory on Speech Recognition in Older Age

Purpose Music training has been proposed as a possible tool for auditory training in older adults, as it may improve both auditory and cognitive skills. However, the evidence to support such benefits is mixed. The goal of this study was to determine the differential effects of lifelong musical training and working memory on speech recognition in noise, in older adults. Method A total of 31 musicians and nonmusicians aged 65-78 years took part in this cross-sectional study. Participants had a normal pure-tone average, with most having high-frequency hearing loss. Working memory (memory capacity) was assessed with the backward Digit Span test, and speech recognition in noise was assessed with three clinical tests (Quick Speech in Noise, Hearing in Noise Test, and Revised Speech Perception in Noise). Results Findings from this sample of older adults indicate that neither music training nor working memory was associated with differences on the speech recognition in noise measures used in this study. Similarly, duration of music training was not associated with speech-in-noise recognition. Conclusions Results from this study do not support the hypothesis that lifelong music training benefits speech recognition in noise. Similarly, an effect of working memory (memory capacity) was not apparent. While these findings may be related to the relatively small sample size, results across previous studies that investigated these effects have also been mixed. Prospective randomized music training studies may be able to better control for variability in outcomes associated with pre-existing and music training factors, as well as to examine the differential impact of music training and working memory for speech-in-noise recognition in older adults.

Use of Music Therapy as an Audiological Rehabilitation Tool in the Elderly Population: A Mini-Review

It is well known and documented that sensory perception decreases with age. In the elderly population, hearing loss and reduced vestibular function are among the most prevalently affected senses. Two important side effects of sensory deprivation are cognitive decline and decrease in social participation. Hearing loss, vestibular function impairment, and cognitive decline all lead to a decrease in social participation. Altogether, these problems have a great impact on the quality of life of the elderly. This is why a rehabilitation program covering all of these aspects would therefore be useful for clinicians. It is well known that long-term music training can lead to cortical plasticity. Behavioral improvements have been measured for cognitive abilities and sensory modalities (auditory, motor, tactile, and visual) in healthy young adults. Based on these findings, it is possible to wonder if this kind of multisensory training would be an interesting therapy to not only improve communication but also help with posture and balance, cognitive abilities, and social participation. The aim of this review is to assess and validate the impact of music therapy in the context of hearing rehabilitation in older adults. Musical therapy seems to have a positive impact on auditory perception, posture and balance, social integration, and cognition. While the benefits seem obvious, the evidence in the literature is scarce. However, there is no reason not to recommend the use of music therapy as an adjunct to audiological rehabilitation in the elderly when possible. Further investigations are needed to conclude on the extent of the benefits that music therapy could bring to older adults. More data are needed to confirm which hearing abilities can be improved based on the many characteristics of hearing loss. There is also a need to provide a clear protocol for clinicians on how this therapy should be administered to offer the greatest possible benefits.

Benefit of Musical Training for Speech Perception and Cognition Later in Life

Purpose The aim of this study was to determine the long-term associations of musical training with speech perception in adverse conditions and cognition in a longitudinal cohort study of middle-age to older adults. Method This study is based on Epidemiology of Hearing Loss Study participants. We asked participants at baseline (1993-1995) about their musical training. Speech perception (word recognition in competing message; Northwestern University Auditory Test Number 6), cognitive function (cognitive test battery), and impairment (self-report or surrogate report of Alzheimer's disease or dementia, and/or a Mini-Mental State Examination score ≤ 24) were assessed up to 5 times over the 20-year follow-up. We included 2,938 Epidemiology of Hearing Loss Study participants who had musical training data and at least one follow-up of speech perception and/or cognitive assessment. We used linear mixed-effects models to determine associations between musicianship and decline in speech perception and cognitive function over time and Cox regression models to evaluate associations of musical training with 20-year cumulative incidence of speech perception and cognitive impairment. Models were adjusted for age, sex, and occupation and repeated with additional adjustment for health-related confounders and education. Results Musicians showed less speech perception decline over time with stronger effects in women (0.16% difference, 95% confidence interval [CI] [0.05, 0.26]). Among men, musicians had, on average, better speech perception than nonmusicians (3.41% difference, 95% CI [0.62, 6.20]) and were less likely to develop a cognitive impairment than nonmusicians (hazard ratio = 0.58, 95% CI [0.37, 0.91]). Conclusions Musicians showed an advantage in speech perception abilities and cognition later in life and less decline over time with different magnitudes of effect sizes in men and women. Associations remained with further adjustment, indicating that some degree of the advantage of musical training is independent of socioeconomic or health differences. If confirmed, these findings could have implications for developing speech perception intervention and prevention strategies. Supplemental Material https://doi.org/10.23641/asha.14825454.

The frontotemporal organization of the arcuate fasciculus and its relationship with speech perception in young and older amateur singers and non-singers

The ability to perceive speech in noise (SPiN) declines with age. Although the etiology of SPiN decline is not well understood, accumulating evidence suggests a role for the dorsal speech stream. While age-related decline within the dorsal speech stream would negatively affect SPiN performance, experience-induced neuroplastic changes within the dorsal speech stream could positively affect SPiN performance. Here, we investigated the relationship between SPiN performance and the structure of the arcuate fasciculus (AF), which forms the white matter scaffolding of the dorsal speech stream, in aging singers and non-singers. Forty-three non-singers and 41 singers aged 20 to 87 years old completed a hearing evaluation and a magnetic resonance imaging session that included High Angular Resolution Diffusion Imaging. The groups were matched for sex, age, education, handedness, cognitive level, and musical instrument experience. A subgroup of participants completed syllable discrimination in the noise task. The AF was divided into 10 segments to explore potential local specializations for SPiN. The results show that, in carefully matched groups of singers and non-singers (a) myelin and/or axonal membrane deterioration within the bilateral frontotemporal AF segments are associated with SPiN difficulties in aging singers and non-singers; (b) the structure of the AF is different in singers and non-singers; (c) these differences are not associated with a benefit on SPiN performance for singers. This study clarifies the etiology of SPiN difficulties by supporting the hypothesis for the role of aging of the dorsal speech stream.

Musical instrument engagement across the life course and episodic memory in late life: An analysis of 60 years of longitudinal data from the Wisconsin Longitudinal Study

BACKGROUND

As the global burden of dementia increases, the absence of treatment underscores the need for identification of factors that may improve cognitive reserve-the ability to stave off cognitive decline in old age. The beneficial association between musical instrument engagement and episodic memory has been identified in children, young adults, and older adults. Yet, previous studies in musical instrument engagement have rarely examined the potential for adolescence and adulthood exposures to independently improve cognition, nor have they been linked with the rate of memory decline over time in older adults. We investigated whether adolescent musical instrument engagement and continued musical instrument engagement over the adult life course were separately associated with higher episodic memory, as well as rate of decline in a large longitudinal cohort.

METHODS

Data were from a prospective cohort of high school graduates from 1957. High school music engagement (HSME) was ascertained through graduate yearbooks and assessed as membership in musical performance groups. A questionnaire was used to assess musical engagement through adulthood (MEA) at ages 35, 55, and 65. The episodic memory score was composed of immediate and delayed recall task scores, and was assessed when participants were aged approximately 65 and 72 years old among 5,718 individuals. Linear mixed models were used to assess the association between music, and memory performance and decline over time.

RESULTS

Of high school graduates who participated in the study, 38.1% played music in high school, and 21.1% played music in adulthood. While musical engagement was more common in those who played in childhood, 40% of those who played continuously as an adult did not play in high school. High HSME (B = 0.348, p = 0.049) and continuous MEA (B = 0.424, p = 0.012) were associated with higher memory scores at age 65 after covariate adjustment. When examining memory decline, the benefits of high HSME decreased over time (B = -0.435, p = 0.048), while the rate of decline did not differ between MEA groups. Exploratory models revealed differential benefits for HSME and immediate recall, and MEA and delayed recall.

CONCLUSION

This study provides further evidence that musical engagement in childhood or adulthood is associated with non-musical cognitive reserve. These two exposures may act differentially in different domains of episodic memory. Further work is needed to determine the relationship between musicianship and the rate of cognitive decline.

The Influence of the Type of Background Noise on Perceptual Learning of Speech in Noise

OBJECTIVES

Auditory perceptual learning studies tend to focus on the nature of the target stimuli. However, features of the background noise can also have a significant impact on the amount of benefit that participants obtain from training. This study explores whether perceptual learning of speech in background babble noise generalizes to other, real-life environmental background noises (car and rain), and if the benefits are sustained over time.

DESIGN

Normal-hearing native English speakers were randomly assigned to a training (n = 12) or control group (n = 12). Both groups completed a pre- and post-test session in which they identified Bamford-Kowal-Bench (BKB) target words in babble, car, or rain noise. The training group completed speech-in-babble noise training on three consecutive days between the pre- and post-tests. A follow up session was conducted between 8 and 18 weeks after the post-test session (training group: n = 9; control group: n = 7).

RESULTS

Participants who received training had significantly higher post-test word identification accuracy than control participants for all three types of noise, although benefits were greatest for the babble noise condition and weaker for the car- and rain-noise conditions. Both training and control groups maintained their pre- to post-test improvement over a period of several weeks for speech in babble noise, but returned to pre-test accuracy for speech in car and rain noise.

CONCLUSION

The findings show that training benefits can show some generalization from speech-in-babble noise to speech in other types of environmental noise. Both groups sustained their learning over a period of several weeks for speech-in-babble noise. As the control group received equal exposure to all three noise types, the sustained learning with babble noise, but not other noises, implies that a structural feature of babble noise was conducive to the sustained improvement. These findings emphasize the importance of considering the background noise as well as the target stimuli in auditory perceptual learning studies.

MEG Intersubject Phase Locking of Stimulus-Driven Activity during Naturalistic Speech Listening Correlates with Musical Training

Musical training is associated with increased structural and functional connectivity between auditory sensory areas and higher-order brain networks involved in speech and motor processing. Whether such changed connectivity patterns facilitate the cortical propagation of speech information in musicians remains poorly understood. We here used magnetoencephalography (MEG) source imaging and a novel seed-based intersubject phase-locking approach to investigate the effects of musical training on the interregional synchronization of stimulus-driven neural responses during listening to naturalistic continuous speech presented in silence. MEG data were obtained from 20 young human subjects (both sexes) with different degrees of musical training. Our data show robust bilateral patterns of stimulus-driven interregional phase synchronization between auditory cortex and frontotemporal brain regions previously associated with speech processing. Stimulus-driven phase locking was maximal in the delta band, but was also observed in the theta and alpha bands. The individual duration of musical training was positively associated with the magnitude of stimulus-driven alpha-band phase locking between auditory cortex and parts of the dorsal and ventral auditory processing streams. These findings provide evidence for a positive relationship between musical training and the propagation of speech-related information between auditory sensory areas and higher-order processing networks, even when speech is presented in silence. We suggest that the increased synchronization of higher-order cortical regions to auditory cortex may contribute to the previously described musician advantage in processing speech in background noise.SIGNIFICANCE STATEMENT Musical training has been associated with widespread structural and functional brain plasticity. It has been suggested that these changes benefit the production and perception of music but can also translate to other domains of auditory processing, such as speech. We developed a new magnetoencephalography intersubject analysis approach to study the cortical synchronization of stimulus-driven neural responses during the perception of continuous natural speech and its relationship to individual musical training. Our results provide evidence that musical training is associated with higher synchronization of stimulus-driven activity between brain regions involved in early auditory sensory and higher-order processing. We suggest that the increased synchronized propagation of speech information may contribute to the previously described musician advantage in processing speech in background noise.

Processing of Degraded Speech in Brain Disorders

The speech we hear every day is typically "degraded" by competing sounds and the idiosyncratic vocal characteristics of individual speakers. While the comprehension of "degraded" speech is normally automatic, it depends on dynamic and adaptive processing across distributed neural networks. This presents the brain with an immense computational challenge, making degraded speech processing vulnerable to a range of brain disorders. Therefore, it is likely to be a sensitive marker of neural circuit dysfunction and an index of retained neural plasticity. Considering experimental methods for studying degraded speech and factors that affect its processing in healthy individuals, we review the evidence for altered degraded speech processing in major neurodegenerative diseases, traumatic brain injury and stroke. We develop a predictive coding framework for understanding deficits of degraded speech processing in these disorders, focussing on the "language-led dementias"-the primary progressive aphasias. We conclude by considering prospects for using degraded speech as a probe of language network pathophysiology, a diagnostic tool and a target for therapeutic intervention.

Listening in complex acoustic scenes

Being able to pick out particular sounds, such as speech, against a background of other sounds represents one of the key tasks performed by the auditory system. Understanding how this happens is important because speech recognition in noise is particularly challenging for older listeners and for people with hearing impairments. Central to this ability is the capacity of neurons to adapt to the statistics of sounds reaching the ears, which helps to generate noise-tolerant representations of sounds in the brain. In more complex auditory scenes, such as a cocktail party — where the background noise comprises other voices, sound features associated with each source have to be grouped together and segregated from those belonging to other sources. This depends on precise temporal coding and modulation of cortical response properties when attending to a particular speaker in a multi-talker environment. Furthermore, the neural processing underlying auditory scene analysis is shaped by experience over multiple timescales.

Effect of Vowel Auditory Training on the Speech-In-Noise Perception among Older Adults with Normal Hearing

Introduction:

Aging reduces the ability to understand speech in noise. Hearing rehabilitation is one of the ways to help older people communicate effectively. This study aimed to investigate the effect of vowel auditory training on the improvement of speech-in-noise (SIN) perception among elderly listeners.

Materials and Methods:

This study was conducted on 36 elderly listeners (17 males and 15 females) with the mean±SD of 67.6±6.33. They had the normal peripheral auditory ability but had difficulties in SIN perception. The samples were randomly divided into two groups of intervention and control. The intervention group underwent vowel auditory training; however, the control group received no training.

Results:

After vowel auditory training, the intervention group showed significant changes in the results of the SIN test at two signal-to-noise ratios of 0 and -10 and the Iranian version of the Speech, Spatial, and Qualities of Hearing Scale, compared to the control group (P<0.001). Regarding the Speech Auditory Brainstem Response test, the F₀ magnitude was higher in the intervention group (8.42±2.26), compared to the control group (6.68±1.87) (P<0.011).

Conclusion:

This study investigated the effect of vowel auditory training on the improvement of SIN perception which could be probably due to better F₀ encoding and receiving. This ability enhancement resulted in the easier perception of speech and its more proper separation from background noise which in turn enhanced the ability of the old people to follow the speech of a specific person and track the discussion.

Musical Experience Offsets Age-Related Decline in Understanding Speech-in-Noise: Type of Training Does Not Matter, Working Memory Is the Key

OBJECTIVES

Speech comprehension under "cocktail party" scenarios deteriorates with age even in the absence of measurable hearing loss. Musical training is suggested to counteract the age-related decline in speech-in-noise (SIN) perception, yet which aspect of musical plasticity contributes to this compensation remains unclear. This study aimed to investigate the effects of musical experience and aging on SIN perception ability. We hypothesized a key mediation role of auditory working memory in ameliorating deficient SIN perception in older adults by musical training.

DESIGN

Forty-eight older musicians, 29 older nonmusicians, 48 young musicians, and 24 young nonmusicians all with (near) normal peripheral hearing were recruited. The SIN task was recognizing nonsense speech sentences either perceptually colocated or separated with a noise masker (energetic masking) or a two-talker speech masker (informational masking). Auditory working memory was measured by auditory digit span. Path analysis was used to examine the direct and indirect effects of musical expertise and age on SIN perception performance.

RESULTS

Older musicians outperformed older nonmusicians in auditory working memory and all SIN conditions (noise separation, noise colocation, speech separation, speech colocation), but such musician advantages were absent in young adults. Path analysis showed that age and musical training had opposite effects on auditory working memory, which played a significant mediation role in SIN perception. In addition, the type of musical training did not differentiate SIN perception regardless of age.

CONCLUSIONS

These results provide evidence that musical training offsets age-related speech perception deficit at adverse listening conditions by preserving auditory working memory. Our findings highlight auditory working memory in supporting speech perception amid competing noise in older adults, and underline musical training as a means of "cognitive reserve" against declines in speech comprehension and cognition in aging populations.

Autodidacticism and Music: Do Self-Taught Musicians Exhibit the Same Auditory Processing Advantages as Formally Trained Musicians?

Multiple studies have demonstrated that musicians have enhanced auditory processing abilities compared to non-musicians. In these studies, musicians are usually defined as having received some sort of formal music training. One issue with this definition is that there are many musicians who are self-taught. The goal of the current study was to determine if self-taught musicians exhibit different auditory enhancements as their formally trained counterparts. Three groups of participants were recruited: formally trained musicians, who received formal music training through the conservatory or private lessons; self-taught musicians, who learned to play music through informal methods, such as with books, videos, or by ear; non-musicians, who had little or no music experience. Auditory processing abilities were assessed using a speech-in-noise task, a passive pitch oddball task done while recording electrical brain activity, and a melodic tonal violation task, done both actively and passively while recording electrical brain activity. For the melodic tonal violation task, formally trained musicians were better at detecting a tonal violation compared to self-taught musicians, who were in turn better than non-musicians. The P600 evoked by a tonal violation was enhanced in formally trained musicians compared to non-musicians. The P600 evoked by an out-of-key note did not differ between formally trained and self-taught musicians, while the P600 evoked by an out-of-tune note was smaller in self-taught musicians compared to formally trained musicians. No differences were observed between the groups for the other tasks. This pattern of results suggests that music training format impacts auditory processing abilities in musical tasks; however, it is possible that these differences arose due to pre-existing factors and not due to the training itself.

Auditory Training to Improve Speech Perception and Self-Efficacy in Aging Adults

Purpose Difficulty in understanding spoken speech is a common complaint among aging adults, even when hearing impairment is absent. Correlational studies point to a relationship between age, auditory temporal processing (ATP), and speech perception but cannot demonstrate causality unlike training studies. In the current study, we test (a) the causal relationship between a spatial-temporal ATP task (temporal order judgment [TOJ]) and speech perception among aging adults using a training design and (b) whether improvement in aging adult speech perception is accompanied by improved self-efficacy. Method Eighty-two participants aged 60-83 years were randomly assigned to a group receiving (a) ATP training (TOJ) over 14 days, (b) non-ATP training (intensity discrimination) over 14 days, or (c) no training. Results The data showed that TOJ training elicited improvement in all speech perception tests, which was accompanied by increased self-efficacy. Neither improvement in speech perception nor self-efficacy was evident following non-ATP training or no training. Conclusions There was no generalization of the improvement resulting from TOJ training to intensity discrimination or generalization of improvement resulting from intensity discrimination training to speech perception. These findings imply that the effect of TOJ training on speech perception is specific and such improvement is not simply the product of generally improved auditory perception. It provides support for the idea that temporal properties of speech are indeed crucial for speech perception. Clinically, the findings suggest that aging adults can be trained to improve their speech perception, specifically through computer-based auditory training, and this may improve perceived self-efficacy.

Musical Training for Auditory Rehabilitation in Hearing Loss

Despite the overall success of cochlear implantation, language outcomes remain suboptimal and subject to large inter-individual variability. Early auditory rehabilitation techniques have mostly focused on low-level sensory abilities. However, a new body of literature suggests that cognitive operations are critical for auditory perception remediation. We argue in this paper that musical training is a particularly appealing candidate for such therapies, as it involves highly relevant cognitive abilities, such as temporal predictions, hierarchical processing, and auditory-motor interactions. We review recent studies demonstrating that music can enhance both language perception and production at multiple levels, from syllable processing to turn-taking in natural conversation.

Music Participation Among School-Aged Children Who Are Hard of Hearing

Purpose Music is an important part of life for many people. Furthermore, music training has been shown to improve a variety of cognitive functions among children and adults. However, little research exists on how children who are hard of hearing (HH) perceive or participate in music. In particular, it is unknown whether hearing loss limits participation in music activities among school-aged children with mild-to-severe hearing loss. The purpose of this study was to determine whether hearing loss limits participation among children who are HH compared to children with normal hearing (NH). Method Participants were parents of 2 cohorts of children finishing 5th grade (approximately 11 years old). Parents were asked to complete a survey (online or paper) regarding the role of music in their child's life. A total of 88 surveys were completed (67 from parents of children who are HH and 21 from parents of children with NH, with an overall response rate of 74%). Results Hearing loss did not limit music participation among children. Children who are HH listened to recorded music, attended live concerts, and practiced an instrument at the same rates as children with NH. Listening to recorded and live music, practicing an instrument, and playing in an ensemble were equally as important to children who are HH as children with NH. Children who are HH were significantly more likely to regularly play in an ensemble than children with NH. Parent participation in music significantly influenced music participation for children who are HH but not children with NH. Descriptive data about music genres, instruments, and ensembles are also presented. Conclusions Children who are HH participate in music at the same or greater rates as children with NH. Parent participation in music may be particularly important for children who are HH. In light of this, music listening should be a consideration when fitting children with hearing aids.

Short-Term Choir Singing Supports Speech-in-Noise Perception and Neural Pitch Strength in Older Adults With Age-Related Hearing Loss

Prior studies have demonstrated musicianship enhancements of various aspects of auditory and cognitive processing in older adults, but musical training has rarely been examined as an intervention for mitigating age-related declines in these abilities. The current study investigates whether 10 weeks of choir participation can improve aspects of auditory processing in older adults, particularly speech-in-noise (SIN) perception. A choir-singing group and an age- and audiometrically-matched do-nothing control group underwent pre- and post-testing over a 10-week period. Linear mixed effects modeling in a regression analysis showed that choir participants demonstrated improvements in speech-in-noise perception, pitch discrimination ability, and the strength of the neural representation of speech fundamental frequency. Choir participants' gains in SIN perception were mediated by improvements in pitch discrimination, which was in turn predicted by the strength of the neural representation of speech stimuli (FFR), suggesting improvements in pitch processing as a possible mechanism for this SIN perceptual improvement. These findings support the hypothesis that short-term choir participation is an effective intervention for mitigating age-related hearing losses.

Keys to staying sharp: A randomized clinical trial of piano training among older adults with and without mild cognitive impairment

BACKGROUND

The prevalence of dementia, the most expensive medical condition (Kirschstein, 2000 and Hurd et al., 2013 [1,2]), and its precursor, mild cognitive impairment (MCI) are increasing [3]. Finding effective intervention strategies to prevent or delay dementia is imperative to public health. Prior research provides compelling evidence that central auditory processing (CAP) deficits are a risk factor for dementia [4-6]. Grounded in the information degradation theory [7, 8], we hypothesize that improving brain function at early perceptual levels (i.e., CAP) may be optimal to attenuate cognitive and functional decline and potentially curb dementia prevalence. Piano training is one avenue to enhance cognition [9-13] by facilitating CAP at initial perceptual stages [14-18].

OBJECTIVES

The Keys To Staying Sharp study is a two arm, randomized clinical trial examining the efficacy of piano training relative to music listening instruction to improve CAP, cognition, and everyday function among older adults. In addition, the moderating effects of MCI status on piano training efficacy will be examined and potential mediators of intervention effects will be explored.

HYPOTHESES

We hypothesize that piano training will improve CAP and cognitive performance, leading to functional improvements. We expect that enhanced CAP will mediate cognitive gains. We further hypothesize that cognitive gains will mediate functional improvements.

METHOD

We plan to enroll 360 adults aged 60 years and older who will be randomized to piano training or an active control condition of music listening instruction and complete pre- and immediate post- assessments of CAP, cognition, and everyday function.

Plasticity in auditory categorization is supported by differential engagement of the auditory-linguistic network

To construct our perceptual world, the brain categorizes variable sensory cues into behaviorally-relevant groupings. Categorical representations are apparent within a distributed fronto-temporo-parietal brain network but how this neural circuitry is shaped by experience remains undefined. Here, we asked whether speech and music categories might be formed within different auditory-linguistic brain regions depending on listeners' auditory expertise. We recorded EEG in highly skilled (musicians) vs. less experienced (nonmusicians) perceivers as they rapidly categorized speech and musical sounds. Musicians showed perceptual enhancements across domains, yet source EEG data revealed a double dissociation in the neurobiological mechanisms supporting categorization between groups. Whereas musicians coded categories in primary auditory cortex (PAC), nonmusicians recruited non-auditory regions (e.g., inferior frontal gyrus, IFG) to generate category-level information. Functional connectivity confirmed nonmusicians' increased left IFG involvement reflects stronger routing of signal from PAC directed to IFG, presumably because sensory coding is insufficient to construct categories in less experienced listeners. Our findings establish auditory experience modulates specific engagement and inter-regional communication in the auditory-linguistic network supporting categorical perception. Whereas early canonical PAC representations are sufficient to generate categories in highly trained ears, less experienced perceivers broadcast information downstream to higher-order linguistic brain areas (IFG) to construct abstract sound labels.

Musical training improves the ability to understand speech-in-noise in older adults

It is well known that hearing abilities decline with age, and one of the most commonly reported hearing difficulties reported in older adults is a reduced ability to understand speech in noisy environments. Older adult musicians have an enhanced ability to understand speech in noise, and this has been associated with enhanced brain responses related to both speech processing and the deployment of attention; however, the causal impact of music lessons in older adults has not yet been demonstrated. To investigate whether a causal relationship exists between short-term musical training and performance on auditory tests in older adults and to determine if musical training can be used to improve hearing in older adult nonmusicians, we conducted a longitudinal training study with random assignment. A sample of older adults was randomly assigned to learn to play piano (Music), to learn to play a visuospatially demanding video game (Video), or to serve as a no-contact control (No-contact). After 6 months, the Music group improved their ability to understand a word presented in loud background noise, whereas the other 2 groups did not. This improvement was related to an increase in positive-going electrical brain activity at fronto-left electrodes 200-1000 ms after the presentation of a word in noise. Source analyses suggest that this activity was due to sources located in the left inferior frontal gyrus and other regions involved in the speech-motor system. These findings support the idea that musical training provides a causal benefit to hearing abilities. Importantly, these findings suggest that musical training could be used as a foundation to develop auditory rehabilitation programs for older adults.

Linguistic, perceptual, and cognitive factors underlying musicians' benefits in noise-degraded speech perception

Previous studies have reported better speech-in-noise (SIN) recognition in musicians relative to nonmusicians while others have failed to observe this "musician SIN advantage." Here, we aimed to clarify equivocal findings and determine the most relevant perceptual and cognitive factors that do and do not account for musicians' benefits in SIN processing. We measured behavioral performance in musicians and nonmusicians on a battery of SIN recognition, auditory backward masking (a marker of attention), fluid intelligence (IQ), and working memory tasks. We found that musicians outperformed nonmusicians in SIN recognition but also demonstrated better performance in IQ, working memory, and attention. SIN advantages were restricted to more complex speech tasks featuring sentence-level recognition with speech-on-speech masking (i.e., QuickSIN) whereas no group differences were observed in non-speech simultaneous (noise-on-tone) masking. This suggests musicians' advantage is limited to cases where the noise interference is linguistic in nature. Correlations showed SIN scores were associated with working memory, reinforcing the importance of general cognition to degraded speech perception. Lastly, listeners' years of music training predicted auditory attention scores, working memory skills, general fluid intelligence, and SIN perception (i.e., QuickSIN scores), implying that extensive musical training enhances perceptual and cognitive skills. Overall, our results suggest (i) enhanced SIN recognition in musicians is due to improved parsing of competing linguistic signals rather than signal-in-noise extraction, per se, and (ii) cognitive factors (working memory, attention, IQ) at least partially drive musicians' SIN advantages.