Auditory temporal-envelope processing in high-functioning children with Autism Spectrum Disorder

Electrophysiological Measures of Listening-in-Noise With and Without Remote Microphone System Use in Autistic and Non-Autistic Youth

OBJECTIVES

This study examined the neural mechanisms by which remote microphone (RM) systems might lead to improved behavioral performance on listening-in-noise tasks in autistic and non-autistic youth.

DESIGN

Cortical auditory evoked potentials (CAEPs) were recorded in autistic (n = 25) and non-autistic (n = 22) youth who were matched at the group level on chronological age ( M = 14.21 ± 3.39 years) and biological sex. Potentials were recorded during an active syllable identification task completed in quiet and in multi-talker babble noise with and without the use of an RM system. The effects of noise and RM system use on speech-sound-evoked P1-N1-P2 responses and the associations between the cortical responses and behavioral performance on syllable identification were examined.

RESULTS

No group differences were observed for behavioral or CAEP measures of speech processing in quiet or in noise. In the combined sample, syllable identification in noise was less accurate and slower than in the quiet condition. The addition of the RM system to the noise condition restored accuracy, but not the response speed, to the levels observed in quiet. The CAEP analyses noted amplitude reductions and latency delays in the noise compared with the quiet condition. The RM system use increased the N1 amplitude as well as reduced and delayed the P2 response relative to the quiet and noise conditions. Exploratory brain-behavior correlations revealed that larger N1 amplitudes in the RM condition were associated with greater behavioral accuracy of syllable identification. Reduced N1 amplitude and accelerated P2 response were associated with shorter syllable identification response times when listening with the RM system.

CONCLUSIONS

Findings suggest that although listening-in-noise with an RM system might remain effortful, the improved signal to noise ratio facilitates attention to the sensory features of the stimuli and increases speech sound identification accuracy.

A Comparison of Listening Skills of Autistic and Non-Autistic Youth While Using and Not Using Remote Microphone Systems

OBJECTIVES

The purposes of this study were to compare (a) listening-in-noise (accuracy and effort) and (b) remote microphone (RM) system benefits between autistic and non-autistic youth.

DESIGN

Groups of autistic and non-autistic youth that were matched on chronological age and biological sex completed listening-in-noise testing when wearing and not wearing an RM system. Listening-in-noise accuracy and listening effort were evaluated simultaneously using a dual-task paradigm for stimuli varying in type (syllables, words, sentences, and passages). Several putative moderators of RM system effects on outcomes of interest were also evaluated.

RESULTS

Autistic youth outperformed non-autistic youth in some conditions on listening-in-noise accuracy; listening effort between the two groups was not significantly different. RM system use resulted in listening-in-noise accuracy improvements that were nonsignificantly different across groups. Benefits of listening-in-noise accuracy were all large in magnitude. RM system use did not have an effect on listening effort for either group. None of the putative moderators yielded effects of the RM system on listening-in-noise accuracy or effort for non-autistic youth that were significant and interpretable, indicating that RM system benefits did not vary according to any of the participant characteristics assessed.

CONCLUSIONS

Contrary to expectations, autistic youth did not demonstrate listening-in-noise deficits compared to non-autistic youth. Both autistic and non-autistic youth appear to experience RM system benefits marked by large gains in listening-in-noise performance. Thus, the use of this technology in educational and other noisy settings where speech perception needs enhancement might be beneficial for both groups of children.

Acoustic and Semantic Processing of Auditory Scenes in Children with Autism Spectrum Disorders

PURPOSE

Processing real-world sounds requires acoustic and higher-order semantic information. We tested the theory that individuals with autism spectrum disorder (ASD) show enhanced processing of acoustic features and impaired processing of semantic information.

METHODS

We used a change deafness task that required detection of speech and non-speech auditory objects being replaced and a speech-in-noise task using spoken sentences that must be comprehended in the presence of background speech to examine the extent to which 7-15 year old children with ASD (n = 27) rely on acoustic and semantic information, compared to age-matched (n = 27) and IQ-matched (n = 27) groups of typically developing (TD) children. Within a larger group of 7-15 year old TD children (n = 105) we correlated IQ, ASD symptoms, and the use of acoustic and semantic information.

RESULTS

Children with ASD performed worse overall at the change deafness task relative to the age-matched TD controls, but they did not differ from IQ-matched controls. All groups utilized acoustic and semantic information similarly and displayed an attentional bias towards changes that involved the human voice. Similarly, for the speech-in-noise task, age-matched-but not IQ-matched-TD controls performed better overall than the ASD group. However, all groups used semantic context to a similar degree. Among TD children, neither IQ nor the presence of ASD symptoms predict the use of acoustic or semantic information.

CONCLUSION

Children with and without ASD used acoustic and semantic information similarly during auditory change deafness and speech-in-noise tasks.

A working taxonomy for describing the sensory differences of autism

BACKGROUND

Individuals on the autism spectrum have been long described to process sensory information differently than neurotypical individuals. While much effort has been leveraged towards characterizing and investigating the neurobiology underlying the sensory differences of autism, there has been a notable lack of consistency in the terms being used to describe the nature of those differences.

MAIN BODY

We argue that inconsistent and interchangeable terminology-use when describing the sensory differences of autism has become problematic beyond mere pedantry and inconvenience. We begin by highlighting popular terms that are currently being used to describe the sensory differences of autism (e.g. "sensitivity", "reactivity" and "responsivity") and discuss why poor nomenclature may hamper efforts towards understanding the aetiology of sensory differences in autism. We then provide a solution to poor terminology-use by proposing a hierarchical taxonomy for describing and referring to various sensory features.

CONCLUSION

Inconsistent terminology-use when describing the sensory features of autism has stifled discussion and scientific understanding of the sensory differences of autism. The hierarchical taxonomy proposed was developed to help resolve lack of clarity when discussing the sensory differences of autism and to place future research targets at appropriate levels of analysis.

Impaired Subcortical Processing of Amplitude-Modulated Tones in Mice Deficient for Cacna2d3, a Risk Gene for Autism Spectrum Disorders in Humans

Temporal processing of complex sounds is a fundamental and complex task in hearing and a prerequisite for processing and understanding vocalization, speech, and prosody. Here, we studied response properties of neurons in the inferior colliculus (IC) in mice lacking Cacna2d3, a risk gene for autism spectrum disorders (ASDs). The α₂δ3 auxiliary Ca²⁺ channel subunit encoded by Cacna2d3 is essential for proper function of glutamatergic synapses in the auditory brainstem. Recent evidence has shown that much of auditory feature extraction is performed in the auditory brainstem and IC, including processing of amplitude modulation (AM). We determined both spectral and temporal properties of single- and multi-unit responses in the IC of anesthetized mice. IC units of α₂δ3^−/− mice showed normal tuning properties yet increased spontaneous rates compared with α₂δ3^+/+. When stimulated with AM tones, α₂δ3^−/− units exhibited less precise temporal coding and reduced evoked rates to higher modulation frequencies (f_m). Whereas first spike latencies (FSLs) were increased for only few modulation frequencies, population peak latencies were increased for f_m ranging from 20 to 100 Hz in α₂δ3^−/− IC units. The loss of precision of temporal coding with increasing f_m from 70 to 160 Hz was characterized using a normalized offset-corrected (Pearson-like) correlation coefficient, which appeared more appropriate than the metrics of vector strength. The processing deficits of AM sounds analyzed at the level of the IC indicate that α₂δ3^−/− mice exhibit a subcortical auditory processing disorder (APD). Similar deficits may be present in other mouse models for ASDs.

Categorical Perception of Pitch Contours and Voice Onset Time in Mandarin-Speaking Adolescents With Autism Spectrum Disorders

Purpose Previous studies have shown enhanced pitch and impaired time perception in individuals with autism spectrum disorders (ASD). However, it remains unclear whether such deviated patterns of auditory processing depending on acoustic dimensions would transfer to the higher level linguistic pitch and time processing. In this study, we compared the categorical perception (CP) of lexical tones and voice onset time (VOT) in Mandarin Chinese, which utilize pitch and time changes, respectively, to convey phonemic contrasts. Method The data were collected from 22 Mandarin-speaking adolescents with ASD and 20 age-matched neurotypical controls. In addition to the identification and discrimination tasks to test CP performance, all the participants were evaluated with their language ability and phonological working memory. Linear mixed-effects models were constructed to evaluate the identification and discrimination scores across different groups and conditions. Results The basic CP pattern of cross-boundary benefit when perceiving both native lexical tones and VOT was largely preserved in high-functioning adolescents with ASD. The degree of CP of lexical tones in ASD was similar to that in typical controls, whereas the degree of CP of VOT in ASD was greatly reduced. Furthermore, the degree of CP of lexical tones correlated with language ability and digit span in ASD participants. Conclusions These findings suggest that the unbalanced acoustic processing capacities for pitch and time can be generalized to the higher level linguistic processing in ASD. Furthermore, the higher degree of CP of lexical tones correlated with better language ability in Mandarin-speaking individuals with ASD.

Cortical Auditory Processing of Simple Stimuli Is Altered in Autism: A Meta-analysis of Auditory Evoked Responses

BACKGROUND

Auditory perceptual abnormalities are common in persons on the autism spectrum. The neurophysiologic underpinnings of these differences have frequently been studied using auditory event-related potentials (ERPs) and event-related magnetic fields (ERFs). However, no study to date has quantitatively synthesized this literature to determine whether early auditory ERP/ERF latencies or amplitudes in autistic persons differ from those of typically developing control subjects.

METHODS

We searched PubMed and ProQuest for studies comparing 1) latencies/amplitudes of P1/M50, N1b, N1c, M100, P2/M200, and/or N2 ERP/ERF components evoked by pure tones and 2) paired-click sensory gating (P1/N1b amplitude suppression) in autistic individuals and typically developing control subjects. Effects were synthesized using Bayesian 3-level meta-analysis.

RESULTS

In response to pure tones, autistic individuals exhibited prolonged P1/M50 latencies (g = 0.341 [95% credible interval = 0.166, 0.546]), prolonged M100 latencies (g = 0.319 [0.093, 0.550]), reduced N1c amplitudes (g = -0.812 [-1.278, -0.187]), and reduced N2 amplitudes (g = -0.374 [-0.633, -0.179]). There were no practically significant group differences in P2/M200 latencies, N2 latencies, P1/M50 amplitudes, N1b amplitudes, M100 amplitudes, or P2/M200 amplitudes. Paired-click sensory gating was also reduced in autistic individuals (g = -0.389 [-0.619, -0.112]), although this effect was primarily driven by smaller responses to the first click stimulus.

CONCLUSIONS

Relative to typically developing control subjects, autistic individuals demonstrate multiple alterations in early cortical auditory processing of simple stimuli. However, most group differences were modest in size and based on small numbers of heterogeneous studies with variable quality. Future work is necessary to understand whether these neurophysiologic measures can predict clinically meaningful outcomes or serve as stratification biomarkers for the autistic population.

Improving Emotion Perception in Children with Autism Spectrum Disorder with Computer-Based Training and Hearing Amplification

Individuals with Autism Spectrum Disorder (ASD) experience challenges with social communication, often involving emotional elements of language. This may stem from underlying auditory processing difficulties, especially when incoming speech is nuanced or complex. This study explored the effects of auditory training on social perception abilities of children with ASD. The training combined use of a remote-microphone hearing system and computerized emotion perception training. At baseline, children with ASD had poorer social communication scores and delayed mismatch negativity (MMN) compared to typically developing children. Behavioral results, measured pre- and post-intervention, revealed increased social perception scores in children with ASD to the extent that they outperformed their typically developing peers post-intervention. Electrophysiology results revealed changes in neural responses to emotional speech stimuli. Post-intervention, mismatch responses of children with ASD more closely resembled their neurotypical peers, with shorter MMN latencies, a significantly heightened P2 wave, and greater differentiation of emotional stimuli, consistent with their improved behavioral results. This study sets the foundation for further investigation into connections between auditory processing difficulties and social perception and communication for individuals with ASD, and provides a promising indication that combining amplified hearing and computer-based targeted social perception training using emotional speech stimuli may have neuro-rehabilitative benefits.

Delayed cortical processing of auditory stimuli in children with autism spectrum disorder: A meta-analysis of electrophysiological studies

Several researchers have hypothesised that individuals with Autism Spectrum Disorder (ASD) show encoding delays in their obligatory event-related potentials (ERPs)/ event-related fields (ERFs) for low-level auditory information compared to neurotypical (NT) samples. However, empirical research has yielded varied findings, such as low-level auditory processing in ASD samples being unimpaired, superior, or impaired compared to NT samples. Diverse outcomes have also been reported for studies investigating ASD-NT differences in functional lateralisation of delays. The lack of consistency across studies has prevented a comprehensive understanding of the overall effects in the autistic population. Therefore, this meta-analysis compared long-latency ERPs and ERFs produced by autistic and NT individuals to non-linguistic auditory stimuli to test, firstly, the robustness of auditory processing differences and, secondly, whether these differences are observed in one or both hemispheres. Nine articles meeting the inclusion criteria were included in the meta-analysis. Meta-analytic results indicated that autistic individuals demonstrate bilaterally delayed P1/ M50 peaks and lateralised delays in the right but not left hemisphere N1/ M100 peak. These results further inform our understanding of auditory processing and lateralisation across the autism spectrum.

A review of decreased sound tolerance in autism: Definitions, phenomenology, and potential mechanisms

Atypical behavioral responses to environmental sounds are common in autistic children and adults, with 50-70 % of this population exhibiting decreased sound tolerance (DST) at some point in their lives. This symptom is a source of significant distress and impairment across the lifespan, contributing to anxiety, challenging behaviors, reduced community participation, and school/workplace difficulties. However, relatively little is known about its phenomenology or neurocognitive underpinnings. The present article synthesizes a large body of literature on the phenomenology and pathophysiology of DST-related conditions to generate a comprehensive theoretical account of DST in autism. Notably, we argue against conceptualizing DST as a unified construct, suggesting that it be separated into three phenomenologically distinct conditions: hyperacusis (the perception of everyday sounds as excessively loud or painful), misophonia (an acquired aversive reaction to specific sounds), and phonophobia (a specific phobia of sound), each responsible for a portion of observed DST behaviors. We further elaborate our framework by proposing preliminary neurocognitive models of hyperacusis, misophonia, and phonophobia that incorporate neurophysiologic findings from studies of autism.

Subclinical Auditory Neural Deficits in Patients With Type 1 Diabetes Mellitus

Supplemental Digital Content is available in the text.

Objectives:

Diabetes mellitus (DM) is associated with a variety of sensory complications. Very little attention has been given to auditory neuropathic complications in DM. The aim of this study was to determine whether type 1 DM (T1DM) affects neural coding of the rapid temporal fluctuations of sounds, and how any deficits may impact on behavioral performance.

Design:

Participants were 30 young normal-hearing T1DM patients, and 30 age-, sex-, and audiogram-matched healthy controls. Measurements included electrophysiological measures of auditory nerve and brainstem function using the click-evoked auditory brainstem response, and of brainstem neural temporal coding using the sustained frequency-following response (FFR); behavioral tests of temporal coding (interaural phase difference discrimination and the frequency difference limen); tests of speech perception in noise; and self-report measures of auditory disability using the Speech, Spatial and Qualities of Hearing Scale.

Results:

There were no significant differences between T1DM patients and controls in the auditory brainstem response. However, the T1DM group showed significantly reduced FFRs to both temporal envelope and temporal fine structure. The T1DM group also showed significantly higher interaural phase difference and frequency difference limen thresholds, worse speech-in-noise performance, as well as lower overall Speech, Spatial and Qualities scores than the control group.

Conclusions:

These findings suggest that T1DM is associated with degraded neural temporal coding in the brainstem in the absence of an elevation in audiometric threshold, and that the FFR may provide an early indicator of neural damage in T1DM, before any abnormalities can be identified using standard clinical tests. However, the relation between the neural deficits and the behavioral deficits is uncertain.

Auditory Brainstem Pathology in Autism Spectrum Disorder: A Review

Atypical responses to sound are common in individuals with autism spectrum disorder (ASD), and growing evidence suggests an underlying auditory brainstem pathology. This review of the literature provides a comprehensive account of the structural and functional evidence for auditory brainstem abnormalities in ASD. The studies reviewed were published between 1975 and 2016 and were sourced from multiple online databases. Indices of both the quantity and quality of the studies reviewed are considered. Findings show converging evidence for auditory brainstem pathology in ASD, although the specific functions and anatomical structures involved remain equivocal. Two main trends emerge from the literature: (1) abnormalities occur mainly at higher levels of the auditory brainstem, according to structural imaging and electrophysiology studies; and (2) brainstem abnormalities appear to be more common in younger than older children with ASD. These findings suggest delayed maturation of neural transmission pathways between lower and higher levels of the brainstem and are consistent with the auditory disorders commonly observed in ASD, including atypical sound sensitivity, poor sound localization, and difficulty listening in background noise. Limitations of existing studies are discussed, and recommendations for future research are offered.

The singular nature of auditory and visual scene analysis in autism

Individuals with autism spectrum disorder often have difficulty acquiring relevant auditory and visual information in daily environments, despite not being diagnosed as hearing impaired or having low vision. Resent psychophysical and neurophysiological studies have shown that autistic individuals have highly specific individual differences at various levels of information processing, including feature extraction, automatic grouping and top-down modulation in auditory and visual scene analysis. Comparison of the characteristics of scene analysis between auditory and visual modalities reveals some essential commonalities, which could provide clues about the underlying neural mechanisms. Further progress in this line of research may suggest effective methods for diagnosing and supporting autistic individuals.This article is part of the themed issue 'Auditory and visual scene analysis'.

Children with autism spectrum disorder have reduced otoacoustic emissions at the 1 kHz mid-frequency region

Autism spectrum disorder (ASD) is a behaviorally diagnosed disorder of early onset characterized by impairment in social communication and restricted and repetitive behaviors. Some of the earliest signs of ASD involve auditory processing, and a recent study found that hearing thresholds in children with ASD in the mid-range frequencies were significantly related to receptive and expressive language measures. In addition, otoacoustic emissions have been used to detect reduced cochlear function in the presence of normal audiometric thresholds. We were interested then to know if otoacoustic emissions in children with normal audiometric thresholds would also reveal differences between children with ASD and typical developing (TD) controls in mid-frequency regions. Our objective was to specifically measure baseline afferent otoacoustic emissions (distortion-product otoacoustic emissions [DPOAEs]), transient-evoked otoacoustic emissions (TrOAEs), and efferent suppression, in 35 children with high-functioning ASD compared with 42 aged-matched TD controls. All participants were males 6-17 years old, with normal audiometry, and rigorously characterized via Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Children with ASD had greatly reduced DPOAE responses in the 1 kHz frequency range, yet had comparable DPOAE responses at 0.5 and 4-8 kHz regions. Furthermore, analysis of the spectral features of TrOAEs revealed significantly decreased emissions in ASD in similar frequencies. No significant differences were noted in DPOAE or TrOAE noise floors, middle ear muscle reflex activity, or efferent suppression between children with ASD and TD controls. In conclusion, attention to specific-frequency deficits using non-invasive measures of cochlear function may be important in auditory processing impairments found in ASD. Autism Res 2017, 10: 337-345. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Fast response to human voices in autism

Individuals with autism spectrum disorders (ASD) are reported to allocate less spontaneous attention to voices. Here, we investigated how vocal sounds are processed in ASD adults, when those sounds are attended. Participants were asked to react as fast as possible to target stimuli (either voices or strings) while ignoring distracting stimuli. Response times (RTs) were measured. Results showed that, similar to neurotypical (NT) adults, ASD adults were faster to recognize voices compared to strings. Surprisingly, ASD adults had even shorter RTs for voices than the NT adults, suggesting a faster voice recognition process. To investigate the acoustic underpinnings of this effect, we created auditory chimeras that retained only the temporal or the spectral features of voices. For the NT group, no RT advantage was found for the chimeras compared to strings: both sets of features had to be present to observe an RT advantage. However, for the ASD group, shorter RTs were observed for both chimeras. These observations indicate that the previously observed attentional deficit to voices in ASD individuals could be due to a failure to combine acoustic features, even though such features may be well represented at a sensory level.

Relations Among Detection of Syllable Stress, Speech Abnormalities, and Communicative Ability in Adults With Autism Spectrum Disorders

PURPOSE

To date, the literature on perception of affective, pragmatic, and grammatical prosody abilities in autism spectrum disorders (ASD) has been sparse and contradictory. It is interesting to note that the primary perception of syllable stress within the word structure, which is crucial for all prosody functions, remains relatively unexplored in ASD. Thus, in the current study, we explored syllable stress perception sensitivity and its relationship to speech production abnormalities and communicative ability in adults with ASD.

METHOD

A same-different syllable stress perception task using pairs of identical 4-syllable words was delivered to 42 adults with/without high-functioning ASD, matched for age, to investigate primary speech perception ability in ASD. Speech production and communicative ability in ASD was measured using the Autism Diagnostic Observation Schedule (Lord et al., 2000).

RESULTS

As predicted, the results showed that adults with ASD were less sensitive in making judgments about syllable stress relative to controls. Also, partial correlations revealed a key association of speech production abnormalities with stress perception sensitivity, rather than communicative ability.

CONCLUSIONS

Our findings provide empirical evidence for deficits on primary syllable stress perception in ASD and its role on sociocommunicative difficulties. This information could facilitate the development of effective interventions for speech and language therapy and social communication.

Fragile spectral and temporal auditory processing in adolescents with autism spectrum disorder and early language delay

We investigated low-level auditory spectral and temporal processing in adolescents with autism spectrum disorder (ASD) and early language delay compared to matched typically developing controls. Auditory measures were designed to target right versus left auditory cortex processing (i.e. frequency discrimination and slow amplitude modulation (AM) detection versus gap-in-noise detection and faster AM detection), and to pinpoint the task and stimulus characteristics underlying putative superior spectral processing in ASD. We observed impaired frequency discrimination in the ASD group and suggestive evidence of poorer temporal resolution as indexed by gap-in-noise detection thresholds. These findings question the evidence of enhanced spectral sensitivity in ASD and do not support the hypothesis of superior right and inferior left hemispheric auditory processing in ASD.

The relationship between auditory processing and restricted, repetitive behaviors in adults with autism spectrum disorders

Current views suggest that autism spectrum disorders (ASDs) are characterised by enhanced low-level auditory discrimination abilities. Little is known, however, about whether enhanced abilities are universal in ASD and how they relate to symptomatology. We tested auditory discrimination for intensity, frequency and duration in 21 adults with ASD and 21 IQ and age-matched controls. Contrary to predictions, there were significant deficits in ASD on all acoustic parameters. The findings suggest that low-level auditory discrimination ability varies widely within ASD and this variability relates to IQ level, and influences the severity of restricted and repetitive behaviours (RRBs). We suggest that it is essential to further our understanding of the potential contributing role of sensory perception ability on the emergence of RRBs.

Auditory processing in fragile x syndrome

Fragile X syndrome (FXS) is an inherited form of intellectual disability and autism. Among other symptoms, FXS patients demonstrate abnormalities in sensory processing and communication. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity in humans with FXS. Consistent with observations in humans, the Fmr1 KO mouse model of FXS also shows evidence of altered auditory processing and communication deficiencies. A well-known and commonly used phenotype in pre-clinical studies of FXS is audiogenic seizures. In addition, increased acoustic startle response is seen in the Fmr1 KO mice. In vivo electrophysiological recordings indicate hyper-excitable responses, broader frequency tuning, and abnormal spectrotemporal processing in primary auditory cortex of Fmr1 KO mice. Thus, auditory hyper-excitability is a robust, reliable, and translatable biomarker in Fmr1 KO mice. Abnormal auditory evoked responses have been used as outcome measures to test therapeutics in FXS patients. Given that similarly abnormal responses are present in Fmr1 KO mice suggests that cellular mechanisms can be addressed. Sensory cortical deficits are relatively more tractable from a mechanistic perspective than more complex social behaviors that are typically studied in autism and FXS. The focus of this review is to bring together clinical, functional, and structural studies in humans with electrophysiological and behavioral studies in mice to make the case that auditory hypersensitivity provides a unique opportunity to integrate molecular, cellular, circuit level studies with behavioral outcomes in the search for therapeutics for FXS and other autism spectrum disorders.

The use of listening devices to ameliorate auditory deficit in children with autism

OBJECTIVES

To evaluate both monaural and binaural processing skills in a group of children with autism spectrum disorder (ASD) and to determine the degree to which personal frequency modulation (radio transmission) (FM) listening systems could ameliorate their listening difficulties.

STUDY DESIGN

Auditory temporal processing (amplitude modulation detection), spatial listening (integration of binaural difference cues), and functional hearing (speech perception in background noise) were evaluated in 20 children with ASD. Ten of these subsequently underwent a 6-week device trial in which they wore the FM system for up to 7 hours per day.

RESULTS

Auditory temporal processing and spatial listening ability were poorer in subjects with ASD than in matched controls (temporal: P = .014 [95% CI -6.4 to -0.8 dB], spatial: P = .003 [1.0 to 4.4 dB]), and performance on both of these basic processing measures was correlated with speech perception ability (temporal: r = -0.44, P = .022; spatial: r = -0.50, P = .015). The provision of FM listening systems resulted in improved discrimination of speech in noise (P < .001 [11.6% to 21.7%]). Furthermore, both participant and teacher questionnaire data revealed device-related benefits across a range of evaluation categories including Effect of Background Noise (P = .036 [-60.7% to -2.8%]) and Ease of Communication (P = .019 [-40.1% to -5.0%]). Eight of the 10 participants who undertook the 6-week device trial remained consistent FM users at study completion.

CONCLUSIONS

Sustained use of FM listening devices can enhance speech perception in noise, aid social interaction, and improve educational outcomes in children with ASD.