Distortion Product Otoacoustic Emission (DPOAE) Growth in Aging Ears with Clinically Normal Behavioral Thresholds.

Age-related hearing loss (ARHL) is a devastating public health issue. To successfully address ARHL using existing and future treatments, it is imperative to detect the earliest signs of age-related auditory decline and understand the mechanisms driving it. Here, we explore early signs of age-related auditory decline by characterizing cochlear function in 199 ears aged 10-65 years, all of which had clinically defined normal hearing (i.e., behavioral thresholds ≤ 25 dB HL from .25 to 8 kHz bilaterally) and no history of noise exposure. We characterized cochlear function by measuring behavioral thresholds in two paradigms (traditional audiometric thresholds from .25 to 8 kHz and Békésy tracking thresholds from .125 to 20 kHz) and distortion product otoacoustic emission (DPOAE) growth functions at f2 = 2, 4, and 8 kHz. Behavioral thresholds through a standard clinical frequency range (up to 8 kHz) showed statistically, but not clinically, significant declines across increasing decades of life. In contrast, DPOAE growth measured in the same frequency range showed clear declines as early 30 years of age, particularly across moderate stimulus levels (L2 = 25-45 dB SPL). These substantial declines in DPOAE growth were not fully explained by differences in behavioral thresholds measured in the same frequency region. Additionally, high-frequency Békésy tracking thresholds above ~11.2 kHz showed frank declines with increasing age. Collectively, these results suggest that early age-related cochlear decline (1) begins as early as the third or fourth decade of life, (2) is greatest in the cochlear base but apparent through the length of the cochlear partition, (3) cannot be detected fully by traditional clinical measures, and (4) is likely due to a complex mix of etiologies.

The Prevalence and Severity of Misophonia in a UK Undergraduate Medical Student Population and Validation of the Amsterdam Misophonia Scale.

Misophonia is a condition of abnormal emotional responses to specific auditory stimuli. There is limited information available on the prevalence of this condition. This study aimed to estimate the prevalence of misophonia in an undergraduate medical student population at the University of Nottingham. A secondary aim of this study was to assess the psychometric validity of the Amsterdam Misophonia Scale (A-Miso-S) questionnaire tool in this population. The A-Miso-S was administered online to medical students at the University of Nottingham. To assess the validity of the A-Miso-S, a factor analysis was conducted. To determine prevalence and severity the results of the questionnaire were quantitatively analysed using SPSS. Actor analysis was conducted. Free text responses to one questionnaire item were analysed using a thematic approach. Responses were obtained from 336 individuals. Clinically significant misophonic symptoms appear to be common, effecting 49.1% of the sample population. This is statistically significantly higher prevalence than previous studies have found (p < 0.00001). Using the classification of the A-Miso-S, mild symptoms were seen in 37%, moderate in 12%, severe in 0.3% of participants. No extreme cases were seen. The A-Miso-S was found to be a uni-factorial tool, with good internal consistency. This study has provided new information on misophonia and validity of the A-Miso-S questionnaire in a sample population of UK undergraduate medical students. The results indicate that misophonia is a phenomenon that a significant proportion of medical students experience though only a small subset experience it severely.

Detection of Age-Related Hearing Losses (ARHL) via Transient-Evoked Otoacoustic Emissions.

PURPOSE: The objective of the study was to identify subjects presenting hearing deficits, specifically age-related hearing losses (ARHL), via objective assessment methodologies. MATERIALS AND METHODS: Initially, 259 subjects (165 men, 94 women) were enrolled in the study. After the application of inclusion criteria, the final number was reduced to 88 subjects (49.8 ± 19.1 ys) subdivided into 64 normal and 83 ARHL cases. The subjects were assessed with traditional audiometry tests and with transiently evoked otoacoustic emissions (TEOAEs). Since each ear has its own acoustic signature, the TEOAE analyses were conducted in terms of ears and not subjects. The TEOAE data were processed by traditional and recurrence quantification analyses, leading to the estimation of the WWR (whole waveform reproducibility) and the new RAD2D (2-dimensional radius) parameters. A plot of WWR vs RAD2D was used to optimize the classification of the cases presenting ARHL. RESULTS: By using a WWR value of 70% as a classifier, the sensitivity of TEOAEs was estimated as 75.9% and the specificity as 89.1%. By using the RAD2D parameter (with a cut-off value of 1.78), a sensitivity value of 80.7% and a specificity value of 71.9% were obtained. When both parameters were used, a sensitivity value of 85.5% and a specificity value of 92.2% were estimated. In the latter classification paradigm, the number of false negatives decreased from 20 to 12 out of 83 ears (14%). CONCLUSION: In adult hearing screening assessments, the proposed method optimizes the identification of subjects with a hearing impairment correlated to the presence of age-related hearing loss.

Use of sound-elicited fetal heart rate accelerations to assess fetal hearing in the second and third trimester.

OBJECTIVES: We previously reported that fetal heart rate (FHR) accelerations could be obtained after fetal sound stimulation. We examined FHR accelerations during 20-37 weeks gestational age (GA) in order to assess the optimal time for the test. METHODS: The fetus was stimulated from the maternal abdomen with pure tone 2000 Hz, 90 dB, 5 s. Changes in the FHR before and after the sound stimulation were measured by a cardiotocometer. RESULTS: Compared with the positive rate of FHR accelerations at 20-21 weeks GA, significant increases were recognized in 26-27, 28 to 29, 30 to 31, and 34-35 weeks GA. Comparing the positive rate of FHR accelerations between the minimal and moderate variability of FHR baseline, no significant differences were observed at 20-27 weeks GA. On the other hand, at 28-37 weeks GA, the positive rate to detect FHR accelerations due to sound stimulation was 100% in moderate FHR baseline variability. CONCLUSION: Considering development of human fetal hearing, the method should be performed between 28 and 37 weeks GA and during moderate FHR variability corresponding to active sleep conditions. The method developed in the present study may provide a promising tool for evaluating the fetal hearing.

Analyzing the FFR: A tutorial for decoding the richness of auditory function.

The frequency-following response, or FFR, is a neurophysiological response to sound that precisely reflects the ongoing dynamics of sound. It can be used to study the integrity and malleability of neural encoding of sound across the lifespan. Sound processing in the brain can be impaired with pathology and enhanced through expertise. The FFR can index linguistic deprivation, autism, concussion, and reading impairment, and can reflect the impact of enrichment with short-term training, bilingualism, and musicianship. Because of this vast potential, interest in the FFR has grown considerably in the decade since our first tutorial. Despite its widespread adoption, there remains a gap in the current knowledge of its analytical potential. This tutorial aims to bridge this gap. Using recording methods we have employed for the last 20 + years, we have explored many analysis strategies. In this tutorial, we review what we have learned and what we think constitutes the most effective ways of capturing what the FFR can tell us. The tutorial covers FFR components (timing, fundamental frequency, harmonics) and factors that influence FFR (stimulus polarity, response averaging, and stimulus presentation/recording jitter). The spotlight is on FFR analyses, including ways to analyze FFR timing (peaks, autocorrelation, phase consistency, cross-phaseogram), magnitude (RMS, SNR, FFT), and fidelity (stimulus-response correlations, response-to-response correlations and response consistency). The wealth of information contained within an FFR recording brings us closer to understanding how the brain reconstructs our sonic world.

Why and how music can be used to rehabilitate and develop speech and language skills in hearing-impaired children.

This paper presents evidence for a strong connection between the development of speech and language skills and musical activities of children and adolescents with hearing impairment and/or cochlear implants. This conclusion is partially based on findings for typically hearing children and adolescents, showing better speech and language skills in children and adolescents with musical training, and importantly, showing increases of speech and language skills in children and adolescents taking part in musical training. Further, studies of hearing-impaired children show connections between musical skills, involvement in musical hobbies, and speech and language skills. Even though the field is still lacking large-scale randomised controlled trials on the effects of musical interventions on the speech and language skills of children and adolescents with hearing impairments and cochlear implants, the current evidence seems enough to urge speech therapists, music therapists, music teachers, parents, and children and adolescents with hearing impairments and/or cochlear implants to start using music for enhancing speech and language skills. For this reason, we give our recommendations on how to use music for language skill enhancement in this group.

A Comparison of Behavioral Methods for Indexing the Auditory Processing of Temporal Fine Structure Cues.

Purpose Growing evidence supports the inclusion of perceptual tests that quantify the processing of temporal fine structure (TFS) in clinical hearing assessment. Many tasks have been used to evaluate TFS in the laboratory that vary greatly in the stimuli used and whether the judgments require monaural or binaural comparisons of TFS. The purpose of this study was to compare laboratory measures of TFS for inclusion in a battery of suprathreshold auditory tests. A subset of available TFS tasks were selected on the basis of potential clinical utility and were evaluated using metrics that focus on characteristics important for clinical use. Method TFS measures were implemented in replication of studies that demonstrated clinical utility. Monaural, diotic, and dichotic measures were evaluated in 11 young listeners with normal hearing. Measures included frequency modulation (FM) tasks, harmonic frequency shift detection, interaural phase difference (TFS-low frequency), interaural time difference (ITD), monaural gap duration discrimination, and tone detection in noise with and without a difference in interaural phase (N0S0, N0Sπ). Data were compared with published results and evaluated with metrics of consistency and efficiency. Results Thresholds obtained were consistent with published data. There was no evidence of predictive relationships among the measures consistent with a homogenous group. The most stable tasks across repeated testing were TFS-low frequency, diotic and dichotic FM, and N0Sπ. Monaural and diotic FM had the lowest normalized variance and were the most efficient accounting for differences in total test duration, followed by ITD. Conclusions Despite a long stimulus duration, FM tasks dominated comparisons of consistency and efficiency. Small differences separated the dichotic tasks FM, ITD, and N0Sπ. Future comparisons following procedural optimization of the tasks will evaluate clinical efficiency in populations with impairment.

Development and evaluation of a tablet-based diagnostic audiometer.

Objective: To develop and evaluate a software application capable of conducting Pure-Tone Audiometry tests in clinical practice. Design: We designed and developed a mobile software application for iPad devices that performs Pure-Tone Audiometry according to ANSI and IEC standards. The application is proposed to be operated by a trained audiologist inside a sound booth. No extra equipment is required. Hence, it updates the procedure by showing the versatility of the proposed system. Particularly, it provides manual and automated measurement, including air- and bone-conduction audiometry. Study sample: Twenty-nine participants-patients of Papageorgiou Hospital, Thessaloniki, Greece were tested, with all degrees of hearing sensitivity. Manual air- and bone-conduction Pure-Tone Audiometry was conducted inside a sound booth. Participants were tested with conventional audiometry and the audiometric application, in order to validate the tablet-based audiometer for measuring hearing thresholds. Results: The majority (90.9%) of air-conduction estimated hearing thresholds and (90.8%) of air-bone gaps were within 5 dB, compared to results obtained by conventional audiometry. Thus, threshold differences were not significant. Conclusions: The proposed audiometer is a reliable and valid tool for hearing assessment. Owing to certain limitations, mobile devices can provide a feasible substitute for conventional audiometry in clinical practice.

Effect of auditory-motor training on auditory processing of school children.

OBJECTIVE: To compare performance in Avaliação Simplificada do Processamento Auditivo Central and Scale of Auditory Behaviors scores before and after auditory and motor training. METHODS: Sample comprising 162 children aged 9 to 11 years and attending public schools in the city of São Paulo (SP), Brazil; 122 out of 162 children were allocated to one of three experimental groups: Multisensory; Auditory/Motor and Motor/Auditory. Experimental groups were submitted to 8 hours of auditory, visuospatial and motor stimulation over the course of 8 weeks. The remaining 40 children formed the Control Group and received no stimulation. RESULTS: Relation between child behavior as perceived by school teachers and auditory test responses revealed that the better the performance in auditory processing assessment, the higher the Scale of Auditory Behaviors scores. CONCLUSION: Auditory and motor training led to improvements in auditory processing skills as rated by Avaliação Simplificada do Processamento Auditivo Central and Scale of Auditory Behaviors; this intervention model proved to be a good tool for use in school settings.

LiCoS: A New Linguistically Controlled Sentences Test to Assess Functional Hearing Performance.

PURPOSE: To overcome the potential tension between clinical and ecological validity in speech audiometric assessment by creating a new set of sentence materials with high linguistic validity for the Dutch-speaking area. METHODS: A linguistic "fingerprint" of modern spoken Dutch and Flemish served to generate a set of sentences recorded from 1 male and 1 female talker. The sentences were presented to 30 normal-hearing listeners in stationary speech noise at a signal-to-noise ratio (SNR) of -5 dB sound pressure level (SPL). A list design criterion was used to achieve perceptive homogeneity across the test lists, by scrambling lists of sentences of different syntactic types while controlling for linguistic complexity. The original set of test materials was narrowed down to 360 sentences, and list equivalency was evaluated at the audiological and linguistic levels. A psychometric curve was generated with a resolution of 2 dB based on a second group of 60 young normal-hearing native speakers of Dutch and Flemish. RESULTS: Sentence understanding showed an average repetition accuracy of 63.40% (SD 1.01) across the lists at an SNR of -5 dB SPL. No significant differences were found between the lists at the level of the individual listener. At the linguistic level, the sentence lists showed an equal distribution of phonological, morphological, and syntactic features. CONCLUSION: LiCoS combines the clinical benefit of acoustic control at the list level with the high ecological validity of linguistically representative test items. The new speech audiometric test is particularly appropriate to assess sentence understanding in individuals who would otherwise exhibit near-ceiling performance when tested with linguistically more simplified test stimuli. In combination with pure tone audiometric assessment, LiCoS provides valuable complementary information with respect to the functional hearing of patients.

Manipulation of Auditory Inputs as Rehabilitation Therapy for Maladaptive Auditory Cortical Reorganization.

Neurophysiological and neuroimaging data suggest that the brains of not only children but also adults are reorganized based on sensory inputs and behaviors. Plastic changes in the brain are generally beneficial; however, maladaptive cortical reorganization in the auditory cortex may lead to hearing disorders such as tinnitus and hyperacusis. Recent studies attempted to noninvasively visualize pathological neural activity in the living human brain and reverse maladaptive cortical reorganization by the suitable manipulation of auditory inputs in order to alleviate detrimental auditory symptoms. The effects of the manipulation of auditory inputs on maladaptively reorganized brain were reviewed herein. The findings obtained indicate that rehabilitation therapy based on the manipulation of auditory inputs is an effective and safe approach for hearing disorders. The appropriate manipulation of sensory inputs guided by the visualization of pathological brain activities using recent neuroimaging techniques may contribute to the establishment of new clinical applications for affected individuals.

Acoustic Reflex Testing in Neonatal Hearing Screening and Subsequent Audiological Evaluation.

Purpose: The aims of the study were to examine the acoustic reflex screening and threshold in healthy neonates and those at risk of hearing loss and to determine the effect of birth weight and gestational age on acoustic stapedial reflex (ASR). Method: We assessed 18 healthy neonates (Group I) and 16 with at least 1 risk factor for hearing loss (Group II); all of them passed the transient evoked otoacoustic emission test that assessed neonatal hearing. The test battery included an acoustic reflex screening with activators of 0.5, 1, 2, and 4 kHz and broadband noise and an acoustic reflex threshold test with all of them, except for the broadband noise activator. Results: In the evaluated neonates, the main risk factors were the gestational age at birth and a low birth weight; hence, these were further analyzed. The lower the gestational age at birth and birth weight, the less likely that an acoustic reflex would be elicited by pure-tone activators. This effect was significant at the frequencies of 0.5, 1, and 2 kHz for gestational age at birth and at the frequencies of 1 and 2 kHz for birth weight. When the broadband noise stimulus was used, a response was elicited in all neonates in both groups. When the pure-tone stimulus was used, the Group II showed the highest acoustic reflex thresholds and the highest percentage of cases with an absent ASR. The ASR threshold varied from 50 to 100 dB HL in both groups. Group II presented higher mean ASR thresholds than Group I, this difference being significant at frequencies of 1, 2, and 4 kHz. Conclusions: Birth weight and gestational age at birth were related to the elicitation of the acoustic reflex. Neonates with these risk factors for hearing impairment were less likely to exhibit the acoustic reflex and had higher thresholds.

The role of auditory evoked potentials and otoacoustic emissions in early detection of hearing abnormalities in Behçet's disease patients. A case control study.

OBJECTIVES: To determine the types and to assess the role of auditory evoked potentials and otoacoustic emissions in early detection of hearing abnormalities in Behçet's disease (BD) patients. Their correlations with disease activity were also considered. METHODS: Thirty patients with BD and thirty apparently sex- and age-matched healthy volunteers were included in this study. Auditory evaluation included pure tone audiometry (PTA), otoacoustic emissions (TEOAEs, DPOAE), auditory brainstem response test (ABR) and cortical auditory evoked potentials (tone and speech CAEPs) for all patients and control. RESULTS: The highest abnormality of CAEP latencies elicited by (500Hz and 1000 Hz) as well as speech stimuli (da and ga) among our BD patients was delayed P1 and N1 waves at 80 dB with greater bilateral affection, as well as significant differences between patients and controls. All our BD patients had a smaller amplitude of distortion product OAE (DPOAE) and S/N ratio at 1, 2, 4, 6 kHZ compared with controls and the differences were highly statistically significant (p=0.0001). CONCLUSIONS: Being one of the autoimmune inner ear diseases (AIED), BD has a definite hearing impairment, even in the presence of normal hearing sensitivity, as evidenced by PTA. BD patients had a sub-clinical cochlear pathology which was not affected by disease activity or different organ affection. DPOAE (S/N ratio) proved to be a sensitive test in detecting minimal changes in cochlear pathology and the latencies of CAEPs (tone and speech) measures were considered as sensitive indicators (100%) of early detection of hearing impairment in BD patients.

Single-ended prediction of listening effort using deep neural networks.

The effort required to listen to and understand noisy speech is an important factor in the evaluation of noise reduction schemes. This paper introduces a model for Listening Effort prediction from Acoustic Parameters (LEAP). The model is based on methods from automatic speech recognition, specifically on performance measures that quantify the degradation of phoneme posteriorgrams produced by a deep neural net: Noise or artifacts introduced by speech enhancement often result in a temporal smearing of phoneme representations, which is measured by comparison of phoneme vectors. This procedure does not require a priori knowledge about the processed speech, and is therefore single-ended. The proposed model was evaluated using three datasets of noisy speech signals with listening effort ratings obtained from normal hearing and hearing impaired subjects. The prediction quality was compared to several baseline models such as the ITU-T standard P.563 for single-ended speech quality assessment, the American National Standard ANIQUE+ for single-ended speech quality assessment, and a single-ended SNR estimator. In all three datasets, the proposed new model achieved clearly better prediction accuracies than the baseline models; correlations with subjective ratings were above 0.9. So far, the model is trained on the specific noise types used in the evaluation. Future work will be concerned with overcoming this limitation by training the model on a variety of different noise types in a multi-condition way in order to make it generalize to unknown noise types.

Effect of auditory-motor training on auditory processing of school children / Efeito do treinamento auditivo-motor no processamento auditivo de escolares

ABSTRACT Objective To compare performance in Avaliação Simplificada do Processamento Auditivo Central and Scale of Auditory Behaviors scores before and after auditory and motor training. Methods Sample comprising 162 children aged 9 to 11 years and attending public schools in the city of São Paulo (SP), Brazil; 122 out of 162 children were allocated to one of three experimental groups: Multisensory; Auditory/Motor and Motor/Auditory. Experimental groups were submitted to 8 hours of auditory, visuospatial and motor stimulation over the course of 8 weeks. The remaining 40 children formed the Control Group and received no stimulation. Results Relation between child behavior as perceived by school teachers and auditory test responses revealed that the better the performance in auditory processing assessment, the higher the Scale of Auditory Behaviors scores. Conclusion Auditory and motor training led to improvements in auditory processing skills as rated by Avaliação Simplificada do Processamento Auditivo Central and Scale of Auditory Behaviors; this intervention model proved to be a good tool for use in school settings.

RESUMO Objetivo Comparar as respostas da Avaliação Simplificada do Processamento Auditivo Central às da Scale of Auditory Behaviors antes e depois de um treinamento auditivo e de habilidades motoras. Métodos Participaram 162 escolares de 9 a 11 anos de escola pública municipal da cidade de São Paulo (SP), sendo 122 deles divididos em três grupos experimentais: Multissensorial; Auditivo/Motor e Motor/Auditivo. Eles receberam estimulação auditiva, visuoespacial e motora durante 8 semanas (8 horas). O Grupo Controle, que não recebeu estimulação, foi formado por 40 escolares. Resultados A relação entre a percepção dos professores sobre o comportamento dos alunos e suas respostas em testes auditivos mostrou que quanto melhor o resultado na avaliação do processamento auditivo, melhores os escores da Scale of Auditory Behaviors. Conclusão Após treinamento auditivo e motor, ocorreu melhora significativa das habilidades do processamento auditivo demonstradas pela Avaliação Simplificada do Processamento Auditivo Central e na Scale of Auditory Behaviors, e este modelo de intervenção consistiu em boa ferramenta para uso na escola.

An overview of cochlear implant electrode array designs.

Cochlear implant electrode arrays are designed with specific characteristics that allow for the preservation of intra-cochlear structures during the insertion process, as well as during explantation. Straight lateral wall (LW) electrode arrays and pre-curved modiolar hugging (MH) electrode arrays are the two types that are commercially available. Although there is a third type of electrode array called the mid-scala (MS), which is positioned in the middle of the scala tympani (ST), and is usually considered as an MH type of electrode. Different lengths of straight LW electrode arrays are currently available which allow for insertion across a range of different sized cochleae; however, due to manufacturing limitations, pre-curved MH electrodes are generally only available to cover the basal turn of the cochlea, while the spiral ganglion cells are distributed in the Rosenthal's canal that extends into 1.75 turns of the cochlea. Both straight LW and pre-curved MH electrodes can cause a certain degree of intra-cochlear trauma, but pre-curved MH electrodes tend to deviate into the scala vestibuli from the scala tympani more often than the straight LW electrodes, resulting in damage to the osseous spiral lamina/spiral ligament which could initiate new bone formation and eventually affect the cochlear implant users' hearing performance. Structural damage to the cochlea could also affect the vestibular function. With pre-curved MH electrodes, higher degrees of trauma are related to the fixed curling geometry of the electrode in relation to the variable coiling pattern of individual cochleae, the orientation of the electrode contacts in relation to the modiolus wall, and how effectively the stylet was handled by the surgeon during the procedure. Wire management, metal density, and the shore hardness of the silicone elastomer all contribute to the stiffness/flexibility of the electrode. It is important to acknowledge the impact of bringing the stimulating contacts closer to the modiolus wall with an MH electrode type in terms of the resultant damage to intra-cochlear structures. The presence of malformed cochleae should be identified and appropriate electrodes should be chosen for each specific cochlea, irrespective of the cochlear implant brand. In order to utilize drug therapy, the cochlea should be free from any trauma.

Development of a method for determining binaural sensitivity to temporal fine structure.

OBJECTIVE: To develop and evaluate a test of the ability to process binaural temporal-fine-structure (TFS) information. The test was intended to provide a graded measure of TFS sensitivity for all listeners. DESIGN: Sensitivity to TFS was assessed at a sensation level of 30 dB using the established TFS-LF test at centre frequencies of 250, 500 and 750 Hz, and using the new TFS-AF test, in which the interaural phase difference (IPD) was fixed and the frequency was adaptively varied. IPDs varied from 30 to 180°. STUDY SAMPLE: Nine young (19-25 years) and 23 older (47-84 years) listeners with normal hearing over the tested frequency range. RESULTS: For the young listeners, thresholds on the TFS-AF test did not improve significantly with repeated testing. The rank-ordering of performance across listeners was independent of the size of the IPD, and moderate-to-strong correlations were observed between scores for the TFS-LF and TFS-AF tests. Older listeners who were unable to complete the TFS-LF test were all able to complete the TFS-AF test. CONCLUSIONS: No practice effects and strong correlations with an established test of binaural TFS sensitivity make the TFS-AF test a good candidate for the assessment of supra-threshold binaural processing.

The MMN as a viable and objective marker of auditory development in CI users.

In the present article, we review the studies on the use of the mismatch negativity (MMN) as a tool for an objective assessment of cochlear-implant (CI) functioning after its implantation and as a function of time of CI use. The MMN indexes discrimination of different sound stimuli with a precision matching with that of behavioral discrimination and can therefore be used as its objective index. Importantly, these measurements can be reliably carried out even in the absence of attention and behavioral responses and therefore they can be extended to populations that are not capable of behaviorally reporting their perception such as infants and different clinical patient groups. In infants and small children with CI, the MMN provides the only means for assessing the adequacy of the CI functioning, its improvement as a function of time of CI use, and the efficiency of different rehabilitation procedures. Therefore, the MMN can also be used as a tool in developing and testing different novel rehabilitation procedures. Importantly, the recently developed multi-feature MMN paradigms permit the objective assessment of discrimination accuracy for all the different auditory dimensions (such as frequency, intensity, and duration) in a short recording time of about 30 min. Most recently, such stimulus paradigms have been successfully developed for an objective assessment of music perception, too.

Speech reception with different bilateral directional processing schemes: Influence of binaural hearing, audiometric asymmetry, and acoustic scenario.

Hearing aid (HA) users can differ markedly in their benefit from directional processing (or beamforming) algorithms. The current study therefore investigated candidacy for different bilateral directional processing schemes. Groups of elderly listeners with symmetric (N = 20) or asymmetric (N = 19) hearing thresholds for frequencies below 2 kHz, a large spread in the binaural intelligibility level difference (BILD), and no difference in age, overall degree of hearing loss, or performance on a measure of selective attention took part. Aided speech reception was measured using virtual acoustics together with a simulation of a linked pair of completely occluding behind-the-ear HAs. Five processing schemes and three acoustic scenarios were used. The processing schemes differed in the tradeoff between signal-to-noise ratio (SNR) improvement and binaural cue preservation. The acoustic scenarios consisted of a frontal target talker presented against two speech maskers from ±60° azimuth or spatially diffuse cafeteria noise. For both groups, a significant interaction between BILD, processing scheme, and acoustic scenario was found. This interaction implied that, in situations with lateral speech maskers, HA users with BILDs larger than about 2 dB profited more from preserved low-frequency binaural cues than from greater SNR improvement, whereas for smaller BILDs the opposite was true. Audiometric asymmetry reduced the influence of binaural hearing. In spatially diffuse noise, the maximal SNR improvement was generally beneficial. N0Sπ detection performance at 500 Hz predicted the benefit from low-frequency binaural cues. Together, these findings provide a basis for adapting bilateral directional processing to individual and situational influences. Further research is needed to investigate their generalizability to more realistic HA conditions (e.g., with low-frequency vent-transmitted sound).

Sensitivity to Angular and Radial Source Movements as a Function of Acoustic Complexity in Normal and Impaired Hearing.

In contrast to static sounds, spatially dynamic sounds have received little attention in psychoacoustic research so far. This holds true especially for acoustically complex (reverberant, multisource) conditions and impaired hearing. The current study therefore investigated the influence of reverberation and the number of concurrent sound sources on source movement detection in young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners. A listening environment based on natural environmental sounds was simulated using virtual acoustics and rendered over headphones. Both near-far ('radial') and left-right ('angular') movements of a frontal target source were considered. The acoustic complexity was varied by adding static lateral distractor sound sources as well as reverberation. Acoustic analyses confirmed the expected changes in stimulus features that are thought to underlie radial and angular source movements under anechoic conditions and suggested a special role of monaural spectral changes under reverberant conditions. Analyses of the detection thresholds showed that, with the exception of the single-source scenarios, the EHI group was less sensitive to source movements than the YNH group, despite adequate stimulus audibility. Adding static sound sources clearly impaired the detectability of angular source movements for the EHI (but not the YNH) group. Reverberation, on the other hand, clearly impaired radial source movement detection for the EHI (but not the YNH) listeners. These results illustrate the feasibility of studying factors related to auditory movement perception with the help of the developed test setup.