Normal linear and non-linear cochlear mechanisms and efferent system functioning in individuals with misophonia.

BACKGROUND: Misophonia, a condition characterized by heightened sensitivity and strong emotional reactions to specific sounds, has sparked considerable interest and debate regarding its underlying auditory mechanisms. The study aimed to understand the auditory underpinnings of two such potential inner ear systems, non-linear and linear outer hair cell functioning along with auditory efferent functioning in individuals with misophonia. METHODS: 40 ears with misophonia (20 participants) and 37 ears without misophonia (20 participants), both having normal hearing sensitivity were included in this study. Transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) were obtained in two conditions (with and without contralateral noise). RESULTS: Results of independent-samples t-test showed no statistically significant difference (p > 0.05) in the absolute amplitudes of both TEOAEs and DPOAEs between the individuals with and without misophonia. There was no statistically significant difference (p > 0.05) observed in the magnitude of suppression amplitude between the two groups for in both TEOAEs and DPOAEs between individuals with and without misophonia. CONCLUSION: These results suggest that the cochlear and efferent auditory underpinnings examined in this study may not be major contributors to the development or manifestation of misophonia.

Differential advantages of musical backgrounds on binaural integration and interaction skills in instrumentalists, vocalists, and non-musicians.

Background: Musical perception requires a host of skills. Instrumental musicians place greater emphasis on motor coordination, whereas vocal musicians rehearse vocal sounds. The study explored the differential advantages of musical background on binaural integration and interaction in musicians (instrumentalists, vocalists) and compared them with age-matched non-musicians. Methods: Eight six participants aged 20-40 y with normal hearing sensitivity were subjected to binaural tests using a standard group comparison research design. The participants were segregated into three groups - Group 1 included instrumentalists (n = 26, mean age: 17.73 ± 2.83 y), while Group 2 and Group 3 consisted of vocalists (n = 30, mean age: 19.30 ± 2.47 y) and non-musicians (n = 30, mean age: 18.20 ± 3.02 y) respectively. The binaural processes namely integration (Dichotic syllable test, DST; and virtual acoustic space identification - VASI) and interaction (Interaural difference thresholds for time and level: ITD & ILD), were administered on all the participants. Results: Statistical analyses showed the main effect of musicianship. Bonferroni pair-wise test revealed that the musicians (instrumentalists and vocalists) outperformed (p < 0.05) non-musicians in all the tests. The differential advantage of the musical background was seen on the binaural integration test with instrumentalists performing better in the VASI test compared to vocalists, and vice-versa for DST. No difference was observed in interaction tasks (ITD & ILD) between vocalists and instrumentalists (p > 0.05). Conclusion: Musical background-induced differential advantages can be reasonably noted in the binaural skills of instrumentalists and vocalists (compared to non-musicians).

Patient-Reported Outcome Measures for Hearing Aid Benefit and Satisfaction: Content Validity and Readability.

PURPOSE: Numerous patient-reported outcome measures (PROMs) are available to measure hearing aid benefit and satisfaction. It is unclear to what extent currently available PROMs on hearing aid outcomes, often developed decades ago, meet current guidelines for good content validity and readability. This study evaluated the content validity and readability of PROMs that focus on perceived hearing aid benefit and/or satisfaction. METHOD: A literature review was conducted to identify eligible instruments. Content validity evaluation included mapping extracted questionnaire items to the World Health Organization's International Classification of Functioning, Disability and Health (ICF) framework. In addition, study design in content validity methodology was evaluated using the COnsensus-based Standards for the selection of health Measurement INstruments study design checklist for PROM instruments. Readability was estimated using the Simple Measure of Gobbledygook measure. RESULTS: Thirteen questionnaires were identified and evaluated. Item content focused primarily on the components of environmental factors as well as activity limitations and participation restrictions with less emphasis on body functions and personal factors. The content validity methodology analysis revealed an underuse or lack of reporting of a qualitative methodology in assessing patient and professional perspectives. All the included questionnaires exceeded the recommended sixth-grade reading level. CONCLUSIONS: The categories covered by hearing aid PROMs vary considerably, with no single instrument comprehensively covering all the key ICF components. Future development of hearing aid outcome measures should consider a mixed methodology approach for improved content validity and ensure an appropriate reading level.

Age differences in binaural and working memory abilities in school-going children.

OBJECTIVES: Binaural hearing is the interplay of acoustic cues (interaural time differences: ITD, interaural level differences: ILD, and spectral cues) and cognitive abilities (e.g., working memory, attention). The current study investigated the effect of developmental age on auditory binaural resolution and working memory and the association between them (if any) in school-going children. METHODS: Fifty-seven normal-hearing school-going children aged 6-15 y were recruited for the study. The participants were divided into three groups: Group 1 (n=17, Mage = 7.1y ± 0.72 y), Group 2 (n = 23; Mage = 10.2y ± 0.8 y), Group 3 (n = 17; Mage: 14.1 y ±1.3 y). Group 4, with normal hearing young adults (n = 20; Mage = 21.1 y± 3.2 y), was included for comparing the maturational changes in former groups with adult values. Tests of binaural resolution (ITD and ILD thresholds) and auditory working memory (forward and backward digit span and 2n-back digit) were administered to all the participants. RESULTS: Results indicated a main effect of age on spatial resolution and working memory, with the median of lower age groups (Group 1 & Group 2) being significantly poorer (p < 0.01) than the higher age groups (Group 3 & Group 4). Groups 2, 3, and 4 performed significantly better than Group 1 (p < 0.001) on the forward span and ILD task. Groups 3 and 4 had significantly better ITD (p = 0.04), backward span (p = 0.02), and 2n-back scores than Group 2. A significant correlation between scores on working memory tasks and spatial resolution thresholds was also found. On discriminant function analysis, backward span and ITD emerged as sensitive measures for segregating older groups (Group 3 & Group 4) from younger groups (Group 1 & Group 2). CONCLUSIONS: The present study showed that the ILD thresholds and forward digit span mature by nine years. However, the backward digit span score continued to mature beyond 15 y. This finding can be attributed to the influence of auditory attention (a working memory process) on the binaural resolution, which is reported to mature till late adolescence.

Test re-test reliability of virtual acoustic space identification (VASI) test in young adults with normal hearing.

Background: Recent developments in virtual acoustic technology has levered promising applications in the field of auditory sciences, especially in spatial perception. While conventional auditory spatial assessment using loudspeakers, interaural differences and/or questionnaires are limited by the availability and cost of instruments, the use of virtual acoustic space identification (VASI) test has widespread applications in spatial test battery as it overcomes these constraints. Purpose: The lack of test-retest reliability data of VASI test narrows its direct application in auditory spatial assessment, which is explored in the present study. Methods: Data from 75 normal-hearing young adults (mean age: 25.11 y ± 4.65 SD) was collected in three sessions: baseline, within 15 min of baseline (intra-session), and one week after baseline session (inter-session). Test-retest reliability was assessed using the intra-class correlation coefficient (ICC), coefficient of variation (CV), and cluster plots. Results: The results showed excellent reliability for both accuracy and reaction time measures of VASI, with ICC values of 0.93 and 0.87, respectively. The CV values for overall VASI accuracy and reaction time 9.66% and 11.88%, respectively. This was also complemented by the cluster plot analyses, which showed 93.33% and 96.00% of temporal stability in the accuracy and reaction time measures, indicative of high test-retest reliability of VASI test in auditory spatial assessment. Conclusions: The high temporal stability (test-retest reliability) of VASI test validates its application in spatial hearing test battery.

Effects of Maturation and Chronological Aging on Auditory Spatial Processing: A Cross-Sectional Study Across Life Span.

OBJECTIVE: The primary aim of the research was to document spatial acuity changes across the life span using a battery of psychoacoustical and perceptual tests. The secondary aim was to identify the optimal metric for measuring spatial processing changes across the life span (ages 10-70 years). DESIGN AND STUDY SAMPLE: A cross-sectional study comprising 115 participants with clinically normal hearing was conducted. Purposive sampling was adopted to recruit participants in the study, who were divided into six groups based on their chronological age. METHOD: Temporal, intensity, spectral, and composite correlates of spatial acuity were assessed using psychoacoustic measures and perceptual questionnaires. The temporal (interaural time difference [ITD]) and intensity correlates (interaural level difference [ILD]) of spatial perception were obtained using a MATLAB (v 2020a), whereas the composite correlate (virtual auditory space identification scores [VASIs]) and perceptual ratings of spatial processing were measured using Paradigm software and speech spatial and qualities in Kannada (SSQ-K). RESULTS: Results across all tests (multivariate analyses variance: 6 age groups × 4 tests, followed by post hoc tests) consistently demonstrate poor ITD and ILD thresholds and overall lower spatial accuracy (VASI, SSQ-K) with increasing age. Discriminant function analyses (DFAs) revealed that VASI had a higher predictive power in capturing age-related changes in auditory spatial processing. The group segregation on spatial performance in DFA became evident after 50 years. CONCLUSION: This study provides evidence of gradual change in all three correlates of spatial processing, with statistically demonstrable deficits appearing from fourth decade of life on VASI and fifth decade of life on binaural processing.

Gender differences in contralateral suppression of spontaneous otoacoustic emissions in individuals with auditory neuropathy spectrum disorders.

PURPOSE: The current study aims to evaluate gender variations in the efferent auditory system functioning in the ANSD population and compare them to normal hearing persons using contralateral suppression of spontaneous OAE (SOAEs). METHODS: For the current study, a total of 54 ears were considered prospectively. 27 ears with normal hearing (NH) sensitivity were in group I, while 27 ears with ANSD were in group II. All of the subjects had a regular audiological examination followed by synchronised SOAE recordings with and without broadband noise (in the contralateral ear) at 50 dB SPL and statistical analysis was carried out. RESULTS: Wilcoxon signed rank test revealed a significant decrease in SOAE amplitude with contralateral noise stimulation in NH, while no such trend was observed in ANSD. However, contralateral SOAE stimulation resulted in significant high-frequency shifts for both the ANSD and NH groups in the noise condition. In the comparison of gender effects on SOAE amplitude and frequency shifts using Mann-Whitney, no significant gender differences were seen. The lack of gender differences in SOAE suppression is explained based on global standing wave theory and local oscillator theory. CONCLUSIONS: Contralateral effect of noise on SOAE shows frequency shifts, but not amplitude shifts both of which are not affected by gender effects.

Profiles and predictors of onset based differences in vocal characteristics of adults with auditory neuropathy spectrum disorder (ANSD).

Purpose: Onset-based differences are understudied in Auditory Neuropathy Spectrum Disorder (ANSD) in dimensions such as voice, which is addressed in the study. The study aimed to profile and predict the best metrics of onset-related differences in acoustic vocal characteristics of early and late-onset ANSD patients. Methods: 31 participants (15 early and 16 late-onset) aged 15-30 years diagnosed with ANSD were included in the study. The sustained phonation of vowel /i/ recorded by the participants using android based smartphones of selected configuration was sent over email to the experimenter. Acoustic parameters (fundamental frequency, harmonic frequencies, jitter, shimmer, harmonic-to-noise ratio, cepstral peak prominence -CPP, and pitch sigma) were analysed using Praat software. Results: Results revealed significantly increased (p < 0.05) fundamental frequency along with decreased F2 and F3 of /i/ in the early-onset ANSD compared to the late-onset group, which can be explained based on differences in the pathophysiology of the disorder. Although not statistically significant, mean perturbations (jitter and shimmer), harmonic-to-noise ratio, cepstral peak prominence, and pitch sigma were more affected in the early-onset group, reflective of lowered auditory feedback and periodicity in their voice samples. Results of discriminant analysis marked the emergence of F2, F3, and CPP as the most sensitive metrics for onset-based group differences in voice characteristics. Conclusions: The findings from the study highlight the role of acoustical voice evaluation (especially CPP, F2 & F3) in verifying the onset of ANSD disorder. The insights from the onset-based differences seen in vocal characteristics can indirectly help audiologists in deciding the management options for ANSD.

Musical Training and Its Association With Age-Related Changes in Binaural, Temporal, and Spatial Processing.

OBJECTIVE: This article aimed to assess the relationship between musical training and age-related changes in binaural, temporal, and spatial processing abilities. DESIGN: A standard group comparison study was conducted involving both musicians and nonmusicians. The effect of musical training was assessed using a battery of psychoacoustical tests (interaural time and level difference thresholds: ITD & ILD, binaural gap detection threshold, and virtual auditory space identification test) and subjective ratings (Spatial-Hearing subsection of Speech, Spatial, and Quality of Hearing scale in Kannada). STUDY SAMPLE: A total of 60 participants, between 41 and 70 years, were divided into three groups of 20 each, based on their age (41-50, 51-60, and 61-70 years). Each of these three groups was subdivided into two, one comprising 10 musicians (vocalists practicing South-Indian classical music) and the other comprising 10 nonmusicians. RESULTS: Multivariate analyses of variance revealed that musicians performed significantly better (p < .001) than nonmusicians in all the tests. Analyses of variance showed that whereas age had no effect (p > .05) on performance in any of the tests in musicians, age affected the performance of nonmusicians significantly in terms of ITD (p = .02) and ILD (p = .01) thresholds. CONCLUSION: Musical training appears to have the potential to slow down age-related decline in binaural, temporal, and spatial processing.

Effects of Spatial Training Paradigms on Auditory Spatial Refinement in Normal-Hearing Listeners: A Comparative Study.

BACKGROUND AND OBJECTIVES: This study compared the effectiveness of two spatial training programs using real and virtual sound sources in refining spatial acuity skills in listeners with normal hearing. SUBJECTS AND METHODS: The study was conducted on two groups of 10 participants each; groups I and II underwent spatial training using real and virtual sound sources, respectively. The study was conducted in three phases: pre-training, training, and post-training phases. At the pre- and post-training phases, the spatial acuity of the participants was measured using real sound sources through the localization test, and virtual sound sources through the virtual acoustic space identification (VASI) test. The thresholds of interaural time difference (ITD) and interaural level difference (ILD) were also measured. In the training phase, Group I participants underwent localization training using loudspeakers in free field, while participants in Group II were subjected to virtual acoustic space (VAS) training using virtual sound sources from headphones. Both the training methods consisted of 5-8 sessions (20 min each) of systematically presented stimuli graded according to duration and back attenuation (for real source training) or number of VAS locations (for virtual source training). RESULTS: Results of independent t-scores comparing the spatial learning scores (pre vs. post-training) for each measure showed differences in performance between the two groups. Group II performed better than Group I on the VASI test, while the Group I out-performed Group II on the ITD. Both groups improved equally on the localization test and ILD. CONCLUSIONS: Based on the present findings, we recommend the use of VAS training as it has practical implications due to its cost effectiveness, need for minimal equipment, and end user usefulness.

Audiological Profiling and Rehabilitation Outcomes in a Child With Johanson-Blizzard Syndrome.

Johanson Blizzard syndrome (JBS) is an autosomal recessive disorder that shows a multi-faceted impact on almost all body functions, including speech and hearing. This case presentation describes the comprehensive audiological and rehabilitative profile of an 8-year-old female child with JBS while correlating the test results to the physiological aspects of hearing. Case history revealed poor developmental motor skills, delayed speech and language development with hypothyroidism, and dysmorphic facial features including low bat ears, micrognathia, high arched palate, and hypoplasia of nasal alae. Conditioned pure-tone audiometric responses revealed profound hearing loss of cochlear origin in both ears, which was substantiated with bilateral A-type tympanogram in immittance evaluation. Otoacoustic emissions and auditory brain stem response were absent in both ears, consistent with the audiometric findings. Rehabilitation attempts with a cochlear implant and hearing aid in the opposite ears showed differential improvements, which were in harmony with the aided thresholds. The physiological basis for each finding and future implications are discussed.

Spatial rehabilitation using virtual auditory space training paradigm in individuals with sensorineural hearing impairment.

Purpose: The present study aimed to quantify the effects of spatial training using virtual sources on a battery of spatial acuity measures in listeners with sensorineural hearing impairment (SNHI). Methods: An intervention-based time-series comparison design involving 82 participants divided into three groups was adopted. Group I (n = 27, SNHI-spatially trained) and group II (n = 25, SNHI-untrained) consisted of SNHI listeners, while group III (n = 30) had listeners with normal hearing (NH). The study was conducted in three phases. In the pre-training phase, all the participants underwent a comprehensive assessment of their spatial processing abilities using a battery of tests including spatial acuity in free-field and closed-field scenarios, tests for binaural processing abilities (interaural time threshold [ITD] and level difference threshold [ILD]), and subjective ratings. While spatial acuity in the free field was assessed using a loudspeaker-based localization test, the closed-field source identification test was performed using virtual stimuli delivered through headphones. The ITD and ILD thresholds were obtained using a MATLAB psychoacoustic toolbox, while the participant ratings on the spatial subsection of speech, spatial, and qualities questionnaire in Kannada were used for the subjective ratings. Group I listeners underwent virtual auditory spatial training (VAST), following pre-evaluation assessments. All tests were re-administered on the group I listeners halfway through training (mid-training evaluation phase) and after training completion (post-training evaluation phase), whereas group II underwent these tests without any training at the same time intervals. Results and discussion: Statistical analysis showed the main effect of groups in all tests at the pre-training evaluation phase, with post hoc comparisons that revealed group equivalency in spatial performance of both SNHI groups (groups I and II). The effect of VAST in group I was evident on all the tests, with the localization test showing the highest predictive power for capturing VAST-related changes on Fischer discriminant analysis (FDA). In contrast, group II demonstrated no changes in spatial acuity across timelines of measurements. FDA revealed increased errors in the categorization of NH as SNHI-trained at post-training evaluation compared to pre-training evaluation, as the spatial performance of the latter improved with VAST in the post-training phase. Conclusion: The study demonstrated positive outcomes of spatial training using VAST in listeners with SNHI. The utility of this training program can be extended to other clinical population with spatial auditory processing deficits such as auditory neuropathy spectrum disorder, cochlear implants, central auditory processing disorders etc.

Musical Aptitude as a Variable in the Assessment of Working Memory and Selective Attention Tasks.

BACKGROUND AND OBJECTIVES: The influence of musical aptitude on cognitive test performance in musicians is a long-debated research question. Evidence points to the low performance of nonmusicians in visual and auditory cognitive tasks (working memory and attention) compared with musicians. This cannot be generalized to all nonmusicians, as a sub-group in this population can have innate musical abilities even without any formal musical training. The present study aimed to study the effect of musical aptitude on the working memory and selective attention. SUBJECTS AND PURPOSE: Three groups of 20 individuals each (a total of 60 participants), including trained-musicians, nonmusicians with good musical aptitude, and nonmusicians with low musical aptitude, participated in the present study. Cognitive-based visual (Flanker's selective attention test) and auditory (working memory tests: backward digit span and operation span) tests were administered. RESULTS: MANOVA (followed by ANOVA) revealed a benefit of musicianship and musical aptitude on backward digit span and Flanker's reaction time (p<0.05). Discriminant function analyses showed that the groups could be effectively (accuracy, 80%) segregated based on the backward digit span and Flanker's selective attention test. Trained musicians and nonmusicians with good musical aptitude were distinguished as one cluster and nonmusicians with low musical aptitude formed another cluster, hinting the role of musical aptitude in working memory and selective attention. CONCLUSIONS: Nonmusicians with good musical aptitude can have enhanced working memory and selective attention skills like musicians. Hence, caution is required when these individuals are included as controls in cognitive-based visual and auditory experiments.

Contralateral Suppression of Spontaneous Otoacoustic Emissions in Individuals With Auditory Neuropathy Spectrum Disorder.

BACKGROUND: The current study attempted to assess efferent auditory system functioning in individuals with auditory neuropathy spectrum disorder (ANSD) using a new approach, contralateral suppression of SOAE, which has not yet been extensively researched. METHODS: Spontaneous otoacoustic emissions (SOAEs) were recorded in a total of 62 ears, divided into 2 groups. Group I comprised of 31 ears with normal hearing (NH), while group II consisted of 31 ears with ANSD. All the participants considered for the study were in the age range of 18-45 years. Synchronized SOAE were recorded using the ILO V6 OAE instrument with and without noise (broadband noise, 50 dB SPL) in the contralateral ear. The frequency and amplitude shifts secondary to the introduction of contralateral noise were analyzed. RESULTS: The results of the study showed a statistically significant high-frequency shift of SOAE with contralateral noise for the NH and ANSD groups. In addition, the NH group also exhibited a statistically significant reduction in SOAE amplitude in contralateral noise conditions. Such a reduction in SOAE amplitude was not observed in individuals with ANSD. CONCLUSION: The absence of suppression of SOAE amplitude suggests efferent damage in individuals with ANSD. The shift in SOAE frequency toward higher frequency in the ANSD group, which is similar to NH group, is suggestive of differential allotment of medial olivocochlear (MOC) mechanism in individuals with ANSD, which codes for contralateral frequency changes and not for amplitude changes.

Virtual Auditory Space Training-Induced Changes of Auditory Spatial Processing in Listeners with Normal Hearing.

OBJECTIVE: Localization involves processing of subtle yet highly enriched monaural and binaural spatial cues. Remediation programs aimed at resolving spatial deficits are surprisingly scanty in literature. The present study is designed to explore the changes that occur in the spatial performance of normal-hearing listeners before and after subjecting them to virtual acoustic space (VAS) training paradigm using behavioral and electrophysiological measures. MATERIALS AND METHODS: Ten normal-hearing listeners participated in the study, which was conducted in three phases, including a pre-training, training, and post-training phase. At the pre- and post-training phases both behavioral measures of spatial acuity and electrophysiological P300 were administered. The spatial acuity of the participants in the free field and closed field were measured apart from quantifying their binaural processing abilities. The training phase consisted of 5-8 sessions (20 min each) carried out using a hierarchy of graded VAS stimuli. RESULTS: The results obtained from descriptive statistics were indicative of an improvement in all the spatial acuity measures in the post-training phase. Statistically, significant changes were noted in interaural time difference (ITD) and virtual acoustic space identification scores measured in the post-training phase. Effect sizes (r) for all of these measures were substantially large, indicating the clinical relevance of these measures in documenting the impact of training. However, the same was not reflected in P300. CONCLUSION: The training protocol used in the present study on a preliminary basis proves to be effective in normal-hearing listeners, and its implications can be extended to other clinical population as well.