Speech perception in tinnitus is related to individual distress level - A neurophysiological study

The impact of tinnitus on speech perception in noise: a systematic review and meta-analysis

PURPOSE

Tinnitus is a condition that causes people to hear sounds without an external source. One significant issue arising from this condition is the difficulty in communicating, especially in the presence of noisy backgrounds. The process of understanding speech in challenging situations requires both cognitive and auditory abilities. Since tinnitus presents unique challenges, it is important to investigate how it affects speech perception in noise.

METHOD

In this review, 32 articles were investigated to determine the effect of tinnitus on the effect of speech in noise perception performance. Based on the meta-analysis performed using a random-effects model, meta-regression was used to explore the moderating effects of age and hearing acuity.

RESULTS

A total of 32 studies were reviewed, and the results of the meta-analysis revealed that tinnitus significantly impacts speech in terms of noise perception performance. Additionally, the regression analysis revealed that age and hearing acuity are not significant predictors of speech in noise perception.

CONCLUSION

Our findings suggest that tinnitus affects speech perception in noisy environments due to cognitive impairments and central auditory processing deficits. Hearing loss and aging also contribute to reduced speech in noise performance. Interventions and further research are necessary to address individual challenges associated with continuous subjective tinnitus.

The role of hidden hearing loss in tinnitus: Insights from early markers of peripheral hearing damage

Since the presence of tinnitus is not always associated with audiometric hearing loss, it has been hypothesized that hidden hearing loss may act as a potential trigger for increased central gain along the neural pathway leading to tinnitus perception. In recent years, the study of hidden hearing loss has improved with the discovery of cochlear synaptopathy and several objective diagnostic markers. This study investigated three potential markers of peripheral hidden hearing loss in subjects with tinnitus: extended high-frequency audiometric thresholds, the auditory brainstem response, and the envelope following response. In addition, speech intelligibility was measured as a functional outcome measurement of hidden hearing loss. To account for age-related hidden hearing loss, participants were grouped according to age, presence of tinnitus, and audiometric thresholds. Group comparisons were conducted to differentiate between age- and tinnitus-related effects of hidden hearing loss. All three markers revealed age-related differences, whereas no differences were observed between the tinnitus and non-tinnitus groups. However, the older tinnitus group showed improved performance on low-pass filtered speech in noise tests compared to the older non-tinnitus group. These low-pass speech in noise scores were significantly correlated with tinnitus distress, as indicated using questionnaires, and could be related to the presence of hyperacusis. Based on our observations, cochlear synaptopathy does not appear to be the underlying cause of tinnitus. The improvement in low-pass speech-in-noise could be explained by enhanced temporal fine structure encoding or hyperacusis. Therefore, we recommend that future tinnitus research takes into account age-related factors, explores low-frequency encoding, and thoroughly assesses hyperacusis.

Comprehensive Characterization of Hearing Loss and Tinnitus in Military-Affiliated and Non-Military-Affiliated Individuals

PURPOSE

Military-affiliated individuals (MIs) are at a higher risk of developing hearing loss and tinnitus. While these disorders are well-studied in MIs, their impact relative to non-military-affiliated individuals (non-MIs) remains understudied. Our study compared hearing, speech-in-noise (SIN) perception, and tinnitus characteristics between MIs and non-MIs.

METHOD

MIs (n = 84) and non-MIs (n = 193) underwent hearing threshold assessment and Quick Speech-in-Noise Test. Participants with tinnitus completed psychoacoustic tinnitus matching, numeric rating scale (NRS) for loudness and annoyance, and Tinnitus Functional Index. Comorbid conditions such as anxiety, depression, and hyperacusis were assessed. We used a linear mixed-effects model to compare hearing thresholds and SIN scores between MIs and non-MIs. A multivariate analysis of variance compared tinnitus characteristics between MIs and non-MIs, and a stepwise regression was performed to identify predictors of tinnitus severity.

RESULTS

MIs exhibited better hearing sensitivity than non-MIs; however, their SIN scores were similar. MIs matched their tinnitus loudness to a lower intensity than non-MIs, but their loudness ratings (NRS) were comparable. MIs reported greater tinnitus annoyance and severity on the relaxation subscale, indicating increased difficulty engaging in restful activities. Tinnitus severity was influenced by hyperacusis and depression in both MIs and non-MIs; however, hearing loss uniquely contributed to severity in MIs.

CONCLUSIONS

Our findings suggest that while MIs may exhibit better or comparable listening abilities, they were significantly more affected by tinnitus than non-MIs. Furthermore, our study highlights the importance of assessing tinnitus-related distress across multiple dimensions, facilitating customization of management strategies for both MIs and non-MIs.

Differential cortical activation patterns: pioneering sub-classification of tinnitus with and without hyperacusis by combining audiometry, gamma oscillations, and hemodynamics

The ongoing controversies about the neural basis of tinnitus, whether linked with central neural gain or not, may hamper efforts to develop therapies. We asked to what extent measurable audiometric characteristics of tinnitus without (T) or with co-occurrence of hyperacusis (TH) are distinguishable on the level of cortical responses. To accomplish this, electroencephalography (EEG) and concurrent functional near-infrared spectroscopy (fNIRS) were measured while patients performed an attentionally demanding auditory discrimination task using stimuli within the individual tinnitus frequency (fTin) and a reference frequency (fRef). Resting-state-fMRI-based functional connectivity (rs-fMRI-bfc) in ascending auditory nuclei (AAN), the primary auditory cortex (AC-I), and four other regions relevant for directing attention or regulating distress in temporal, parietal, and prefrontal cortex was compiled and compared to EEG and concurrent fNIRS activity in the same brain areas. We observed no group differences in pure-tone audiometry (PTA) between 10 and 16 kHz. However, the PTA threshold around the tinnitus pitch was positively correlated with the self-rated tinnitus loudness and also correlated with distress in T-groups, while TH experienced their tinnitus loudness at minimal loudness levels already with maximal suffering scores. The T-group exhibited prolonged auditory brain stem (ABR) wave I latency and reduced ABR wave V amplitudes (indicating reduced neural synchrony in the brainstem), which were associated with lower rs-fMRI-bfc between AAN and the AC-I, as observed in previous studies. In T-subjects, these features were linked with elevated spontaneous and reduced evoked gamma oscillations and with reduced deoxygenated hemoglobin (deoxy-Hb) concentrations in response to stimulation with lower frequencies in temporal cortex (Brodmann area (BA) 41, 42, 22), implying less synchronous auditory responses during active auditory discrimination of reference frequencies. In contrast, in the TH-group gamma oscillations and hemodynamic responses in temporoparietal regions were reversed during active discrimination of tinnitus frequencies. Our findings suggest that T and TH differ in auditory discrimination and memory-dependent directed attention during active discrimination at either tinnitus or reference frequencies, offering a test paradigm that may allow for more precise sub-classification of tinnitus and future improved treatment approaches.

Deficient central mechanisms in tinnitus: Exploring the impact on speech comprehension and executive functions

Many individuals with chronic subjective tinnitus report significant problems in comprehending speech in adverse listening situations. A large body of studies has provided evidence to support the notion that deficits in speech-in-noise (SIN) are prevalent in the tinnitus population, while some studies have challenged these findings. Elemental auditory perception is usually only minimally or not impaired. In addition, deficits in cognitive functions, particularly executive functions, have also been observed in individuals with tinnitus. Given these previous findings, we theorize that deficient central mechanisms may be responsible for the reported speech comprehension problems in tinnitus. 25 participants suffering from chronic subjective tinnitus and 25 control participants, between 23 and 58 years of age, were examined in a cross-sectional design. The groups were case-matched for age, sex, education, and hearing loss. A large audiometric battery was used ranging from threshold and supra-threshold tasks to spoken sentence level speech tasks. Additionally, four cognitive tests were performed, primarily covering the area of executive functions. Tinnitometry and tinnitus-related questionnaires were applied to complement sample description and allow for secondary analyses. We hypothesized that tinnitus participants score lower in complex speech comprehension tasks and executive function tasks compared to healthy controls, while no group differences in elementary audiometric tasks were expected. As expected, individuals with chronic subjective tinnitus scored lower in the SIN and gated speech task, while there were no differences in the basic speech recognition threshold task and the other elementary auditory perception tasks. The cognitive tests revealed clear deficits in interference control in the Stroop task, but not in the Flanker task, in the tinnitus group. There were no differences in inhibition or working memory tasks. Our results clearly delineate differences between tinnitus individuals and control participants in two tests on speech intelligibility under adverse listening conditions. Further, the poorer performance in a task of interference control in individuals with tinnitus points towards an impaired central executive control in individuals with tinnitus. Taken together, our (partly) exploratory study provides novel evidence to the view that deficient central executive system in individuals with tinnitus probably account for impaired speech comprehension.

Tinnitus and Influencing Comorbidities

Numerous studies show that impairments in chronic tinnitus are closely connected with psychosomatic and other concomitant symptoms. This overview summarizes some of these studies. Beyond hearing loss, individual interactions of medical and psychosocial stress factors as well as resources are of central importance. Tinnitus related distress reflects a large number of intercorrelated, psychosomatic influences - such as personality traits, stress reactivity and depression or anxiety - which can be accompanied by cognitive difficulties and should be conceptualized and assessed within a vulnerability-stress-reaction model. Superordinate factors such as age, gender or education level can increase vulnerability to stress. Therefore, diagnosis and therapy of chronic tinnitus be individualised, multidimensional and interdisciplinary. Multimodal psychosomatic therapy approaches aim to address individually constellated medical, audiological and psychological influences in order to sustainably increase the quality of life of those affected. Counselling in the first contact is also indispensable for diagnosis and therapy.

DSLchild-Algorithm-Based Hearing Aid Fitting Can Improve Speech Comprehension in Mildly Distressed Patients with Chronic Tinnitus and Mild-to-Moderate Hearing Loss

Background: Patients with chronic tinnitus and mild-to-moderate hearing loss (HL) can experience difficulties with speech comprehension (SC). The present study investigated SC benefits of a two-component hearing therapy. Methods: One-hundred-seventy-seven gender-stratified patients underwent binaural DSL_child-algorithm-based hearing aid (HA) fitting and conducted auditory training exercises. SC was measured at four timepoints under three noise interference conditions each (0, 55, and 65 dB): after screening (t₀; without HAs), HA- fitting (t₁), additional auditory training (t₂), and at 70-day follow-up (t₃). Repeated-measure analyses of covariance investigated the effects of HAs (t₀–t₁), auditory training (t₁–t₂), and the stability of the combined effect (t₂–t₃) on SC per noise interference level and HL subgroup. Correlational analyses examined associations between SC, age, and psychological indices. Results: Patients showed mildly elevated tinnitus-related distress, which was negatively associated with SC in patients with mild but not moderate HL. At 0 dB, the intervention lastingly improved SC for patients with mild and moderate HL; at 55 dB, for patients with mild HL only. These effects were mainly driven by HAs. Conclusions: The here-investigated treatment demonstrates some SC-benefit under conditions of no or little noise interference. The auditory training component warrants further investigation regarding non-audiological treatment outcomes.

Influence of tinnitus annoyance on hearing-related quality of life in cochlear implant recipients

Tinnitus is a common symptom in cochlear implant (CI) recipients. There is no clear evidence of the influence of tinnitus on hearing-related quality of life (QoL) in this population. The aim of this study was to assess the relationship between hearing-related QoL measured by the Speech, Spatial and Qualities of Hearing scale (SSQ12) and tinnitus annoyance or perceived change in tinnitus annoyance after cochlear implantation. The study sample consisted of 2322 implanted adults across France, Germany, Ireland, Italy, the Netherlands, Sweden and the United Kingdom. Information relating to QoL measured using the SSQ12 and tinnitus annoyance and change in tinnitus annoyance, assessed using single-item questions, were collected one or more years post-implantation. The relationship between SSQ12 score and tinnitus annoyance or change in tinnitus annoyance was analysed using linear models adjusted for age and unilateral versus bilateral implants. Tukey pairwise tests were used to compare mean SSQ12 scores across levels of tinnitus annoyance and changes. Tinnitus prevalence was 33.9% post-implantation. Recipients with tinnitus had a significantly lower SSQ12 score than recipients without tinnitus. SSQ scores varied significantly with tinnitus annoyance, age and unilateral versus bilateral implants. Overall, CI recipients who experienced less bothersome tinnitus reported better hearing-related QoL. Healthcare professionals should be aware of the influence of tinnitus on CI recipients' hearing to manage patient expectations.

The Relationship Between Tinnitus Pitch, Audiogram Edge Frequency, and Auditory Stream Segregation Abilities in Individuals With Tinnitus

Purpose Around 80%-93% of the individuals with tinnitus have hearing loss. Researchers have found that tinnitus pitch was related to the frequencies of hearing loss, but unclear about the relationship between tinnitus pitch and audiometry edge frequency. The comorbidity of tinnitus and speech perception in noise problems had also been reported, but the relationship between tinnitus pitch and speech perception in noise had seldom been investigated. This study was designed to estimate the relationship between tinnitus pitch, audiogram edge frequency, and speech perception in noise. The speech perception in noise was measured using auditory stream segregation paradigm. Method Thirteen individuals with bilateral mild-to-severe tonal tinnitus and minimal-to-mild cochlear hearing loss were selected. Thirteen individuals with hearing loss without tinnitus were also selected. The audiogram of each participant with tinnitus was matched with that of the participant without tinnitus. Tinnitus pitch of the participants with tinnitus was measured and compared with audiogram edge frequency. The stream segregation thresholds were calculated at the participants' admitted tinnitus pitch and one octave below the tinnitus pitch. The stream segregation thresholds were estimated at fission and fusion boundary using pure-tone stimuli in ABA paradigm. Results High correlation between tinnitus pitch and audiogram edge frequency was noted. Overall stream segregation thresholds were higher for individuals with tinnitus. Higher thresholds indicated poorer stream segregation abilities. Within tinnitus participants, the thresholds were significantly lesser at frequency corresponding to admitted tinnitus pitch than at one octave below the tinnitus pitch. Conclusions The information from this study may be helpful in educating the patients about the relationship between hearing loss and tinnitus. The findings may also account for speech-perception-in-noise difficulties often reported by the individuals with tinnitus.

On the relationship between tinnitus distress, cognitive performance and aging

In this study we analyzed psychometric data of 107 individuals who suffer from chronic subjective tinnitus. In particular, we elucidated the relationship between tinnitus-related distress, psychological comorbidities, age, and hearing, and the performance in cognitive concentration and interference tests. Previous research has provided first evidence that individuals with tinnitus may have deficits in cognitive tasks. The present study aimed at extending former research by investigating the relationship between tinnitus distress and cognition. Statistical analyses comprised correlation and regression approaches. We observed a significant relationship between tinnitus distress (tinnitus score, TQ), age and hearing loss and the performance in tests on selective and sustained attention (d2 test) and cognitive interference (Stroop test). Tinnitus distress was identified as the most important predictor of cognitive performance (additionally age for cognitive interference). For other psychometric variables (perceived stress, PSQ; self-efficacy, optimism and pessimism, SWOP) and hearing loss we could not find any meaningful relationship with cognitive performance. The results clearly point to a (currently non-causal) relationship between cognitive skills and distress of tinnitus-related symptoms. Furthermore, the influence of age is noteworthy as this finding implies that with increasing age an appropriate coping with aversive tinnitus symptoms based on proper cognitive functions and age-related hearing dysfunctions, namely inhibition, may become more difficult. Hence, it is suggested to consider cognitive tests as a supplementary measurement in clinical assessment of tinnitus and to raise awareness for the impairing influence of tinnitus on cognition in daily life.

The impact of tinnitus distress on cognition

Tinnitus is the chronic perception of a phantom sound with different levels of related distress. Past research has elucidated interactions of tinnitus distress with audiological, affective and further clinical variables. The influence of tinnitus distress on cognition is underinvestigated. Our study aims at investigating specific influences of tinnitus distress and further associated predictors on cognition in a cohort of n = 146 out-ward clinical tinnitus patients. Age, educational level, hearing loss, Tinnitus Questionnaire (TQ) score, tinnitus duration, speech in noise (SIN), stress, anxiety and depression, and psychological well-being were included as predictors of a machine learning regression approach (elastic net) in three models with scores of a multiple choice vocabulary test (MWT-B), or two trail-making tests (TMT-A and TMT-B), as dependent variables. TQ scores predicted lower MWT-B scores and higher TMT-B test completion time. Stress, emotional, and psychological variables were not found to be relevant predictors in all models with the exception of small positive influences of SIN and depression on TMT-B. Effect sizes were small to medium for all models and predictors. Results are indicative of specific influence of tinnitus distress on cognitive performance, especially on general or crystallized intelligence and executive functions. More research is needed at the delicate intersection of tinnitus distress and cognitive skills needed in daily functioning.

The BDNF Val66Met polymorphism regulates vulnerability to chronic stress and phantom perception

Auditory phantom percepts, such as tinnitus, are a heterogeneous condition with great interindividual variations regarding both the percept itself and its concomitants. Tinnitus causes a considerable amount of distress, with as many as 25% of affected people reporting that it interferes with their daily lives. Although previous research gives an idea about the neural correlates of tinnitus-related distress, it cannot explain why some tinnitus patients develop distress and while others are not bothered by their tinnitus. BDNF Val⁶⁶Met polymorphism (rs6265) is a known risk factor for affective disorders due to its common frequency and established functionality. To elucidate, we explore the neural activation pattern of tinnitus associated with the BDNF Val⁶⁶Met polymorphism using electrophysiological data to assess activity and connectivity changes. A total of 110 participants (55 tinnitus and 55 matched control subjects) were included. In this study, we validate that the BDNF Val⁶⁶Met polymorphism plays an important role in the susceptibility to the clinical manifestation of tinnitus-related distress. We demonstrate that Val/Met carriers have increased alpha power in the subgenual anterior cingulate cortex that correlates with distress levels. Furthermore, distress mediates the relationship between BDNF Val⁶⁶Met polymorphism and tinnitus loudness. In other words, for Val/Met carriers, the subgenual anterior cingulate cortex sends distress-related information to the parahippocampus, which likely integrates the loudness and distress of the tinnitus percept.

Phonetic perception but not perception of speaker gender is impaired in chronic tinnitus

While tinnitus is known to compromise the perception of speech, it is unclear if the same holds for extralinguistic speaker information. Furthermore, research with simple tone stimuli showed that unilateral tinnitus binds spatial attention, thereby impeding the detection of auditory changes in the non-affected ear. Using dichotic listening tasks, we tested left-ear tinnitus patients and control patients for their ability to ignore speech and speaker information in the task-irrelevant ear. To this end they heard vowel-consonant-vowel (VCV) syllables simultaneously spoken by gender-ambiguous voices in one ear and male or female voices in the contralateral ear. They selectively attended to speech (Exp. 1) or speaker (Exp. 2) information in a designated target ear, by classifying either the consonant (/b/ or /g/) in VCV syllables or voice gender (male or female) while ignoring distractor voices in the other ear. While performance was comparable across groups in the gender task, tinnitus patients responded slower than controls in the consonant task, with no effect of target ear. This suggests that tinnitus hampers phonetic perception in speech, while preserving the processing of extralinguistic speaker information. These findings support the growing evidence for speech perception impairments in tinnitus.

Sound therapy for cochlear implant users with tinnitus

OBJECTIVE

Despite the positive effect of a cochlear implant (CI) on tinnitus in many patients, tinnitus remains a problem for a significant proportion of CI users. We investigated the acceptability and effect of sound therapy (a combination of natural background sounds and one concise tinnitus counselling session) on tinnitus and speech perception in CI users who still experienced tinnitus during CI use.

DESIGN AND STUDY SAMPLE

Thirty-two CI users (32-78 years) participated in phase 1: a test at the clinic to evaluate six background sounds provided by the sound processor. Eighteen out of the 32 CI users participated in phase 2: an optional take-home evaluation of 2 weeks without sound therapy, followed by 5 weeks with sound therapy, ending with an evaluation visit.

RESULTS

Thirty subjects (93.8%) found at least one background sound acceptable. In phase 2, a small improvement with sound therapy was found for tinnitus loudness, annoyance, and intrusiveness. 50% of the subjects subjectively reported benefit of sound therapy. Especially the sense of control on their tinnitus was highly appreciated. No detrimental effect on speech perception was observed.

CONCLUSION

The background sounds were acceptable and provided tinnitus relief in some CI users with tinnitus during CI use.

Tinnitus Does Not Interfere with Auditory and Speech Perception

Tinnitus is a sound heard by 15% of the general population in the absence of any external sound. Because external sounds can sometimes mask tinnitus, tinnitus is assumed to affect the perception of external sounds, leading to hypotheses such as "tinnitus filling in the temporal gap" in animal models and "tinnitus inducing hearing difficulty" in human subjects. Here we compared performance in temporal, spectral, intensive, masking and speech-in-noise perception tasks between 45 human listeners with chronic tinnitus (18 females and 27 males with a range of ages and degrees of hearing loss) and 27 young, normal-hearing listeners without tinnitus (11 females and 16 males). After controlling for age, hearing loss, and stimulus variables, we discovered that, contradictory to the widely held assumption, tinnitus does not interfere with the perception of external sounds in 32 of the 36 measures. We interpret the present result to reflect a bottom-up pathway for the external sound and a separate top-down pathway for tinnitus. We propose that these two perceptual pathways can be independently modulated by attention, which leads to the asymmetrical interaction between external and internal sounds, and several other puzzling tinnitus phenomena such as discrepancy in loudness between tinnitus rating and matching. The present results suggest not only a need for new theories involving attention and central noise in animal tinnitus models but also a shift in focus from treating tinnitus to managing its comorbid conditions when addressing complaints about hearing difficulty in individuals with tinnitus.SIGNIFICANCE STATEMENT Tinnitus, or ringing in the ears, is a neurologic disorder that affects 15% of the general population. Here we discovered an asymmetrical relationship between tinnitus and external sounds: although external sounds have been widely used to cover up tinnitus, tinnitus does not impair, and sometimes even improves, the perception of external sounds. This counterintuitive discovery contradicts the general belief held by scientists, clinicians, and even individuals with tinnitus themselves, who often report hearing difficulty, especially in noise. We attribute the counterintuitive discovery to two independent pathways: the bottom-up perception of external sounds and the top-down perception of tinnitus. Clinically, the present work suggests a shift in focus from treating tinnitus itself to treating its comorbid conditions and secondary effects.

Comparison of Amplitude Modulated Sounds and Pure Tones at the Tinnitus Frequency: Residual Tinnitus Suppression and Stimulus Evaluation

Recent studies have compared tinnitus suppression, or residual inhibition, between amplitude- and frequency-modulated (AM) sounds and noises or pure tones (PT). Results are indicative, yet inconclusive, of stronger tinnitus suppression of modulated sounds especially near the tinnitus frequency. Systematic comparison of AM sounds at the tinnitus frequency has not yet been studied in depth. The current study therefore aims at further advancing this line of research by contrasting tinnitus suppression profiles of AM and PT sounds at the matched tinnitus frequency (i.e., 10 and 40 Hz AM vs. PT). Participants with chronic, tonal tinnitus (n = 29) underwent comprehensive psychometric, audiometric, tinnitus matching, and acoustic stimulation procedures. Stimuli were presented for 3 minutes in two loudness regimes (60 dB sensation level [SL], minimum masking level [MML] + 6 dB, control sound: SL -6 dB) and amplitude modulated with 0, 10, or 40 Hz. Tinnitus loudness suppression was measured after the stimulation every 30 seconds. In addition, stimuli were rated regarding their valence and arousal. Results demonstrate only trends for better tinnitus suppression for the 10 Hz modulation and presentation level of 60 dB SL compared with PT, whereas nonsignificant results are reported for 40 Hz and MML + 6 dB, respectively. Furthermore, the 10 Hz AM at 60 dB SL and the 40 Hz AM at MML + 6 dB (trend) stimuli were better tolerated as elicited by valence ratings. We conclude that 10 Hz AM sounds at the tinnitus frequency may be useful to further elucidate the phenomenon of residual inhibition.