Effectiveness of low-cut modified amplification strategy and channel-free hearing aid in individuals with auditory neuropathy spectrum disorder.

OBJECTIVE: The present study attempted to compare the aided benefit using low-cut modified amplification and channel-free hearing aids in individuals with auditory neuropathy spectrum disorder (ANSD). It was also attempted to determine these effects in good and poor performers with ANSD. DESIGN: Cross-sectional within group pretest, post-test design. STUDY SAMPLE: Twenty-five individuals with acquired ANSD were selected for the study. The study sample included 11 males and 14 females between the age ranges of 17-40 years (mean age of 24.6 years). RESULTS: The results of the repeated measures analysis of variance (ANOVA) showed that aided benefit was significantly higher with the channel-free hearing aid. Mixed ANOVA results showed that the improvement was more in good performers than poor performers with ANSD. Multiple regression analyses showed that speech identification scores are a strong predictor of aided benefit. CONCLUSIONS: The results of the present study suggest that channel-free hearing aids and low-cut modified amplification can be used as an efficient alternative technique during hearing aid fitting for individuals with ANSD. However, further evidence-based studies on a larger group are essential to validate the results.

Cortical development and neuroplasticity in Auditory Neuropathy Spectrum Disorder.

Cortical development is dependent to a large extent on stimulus-driven input. Auditory Neuropathy Spectrum Disorder (ANSD) is a recently described form of hearing impairment where neural dys-synchrony is the predominant characteristic. Children with ANSD provide a unique platform to examine the effects of asynchronous and degraded afferent stimulation on cortical auditory neuroplasticity and behavioral processing of sound. In this review, we describe patterns of auditory cortical maturation in children with ANSD. The disruption of cortical maturation that leads to these various patterns includes high levels of intra-individual cortical variability and deficits in cortical phase synchronization of oscillatory neural responses. These neurodevelopmental changes, which are constrained by sensitive periods for central auditory maturation, are correlated with behavioral outcomes for children with ANSD. Overall, we hypothesize that patterns of cortical development in children with ANSD appear to be markers of the severity of the underlying neural dys-synchrony, providing prognostic indicators of success of clinical intervention with amplification and/or electrical stimulation. This article is part of a Special Issue entitled .

Effect of companding on speech recognition in quiet and noise for listeners with ANSD.

OBJECTIVE: The present study assesses the effect of companding on speech perception in quiet and noise for listeners with auditory neuropathy spectrum disorder (ANSD). DESIGN: Speech perception was assessed using speech reception threshold in noise (SRTn) for sentences and consonant identification in quiet and at different signal-to-noise ratios (15, 10, 5, and 0 dB SNR). STUDY SAMPLE: Ten ANSD listeners and normal-hearing listeners participated in the study. RESULTS: ANSD listeners required significantly higher SRTn when compared to the normal-hearing listeners. Companding reduced SRTn more significantly in listeners with ANSD, but for normal-hearing listeners there was only a marginal reduction. In the consonant identification task, ANSD listeners performed poorer than normal-hearing listeners in quiet and noise. Companding improved consonant identification in quiet and at 15 dB SNR for listeners with ANSD, whereas no improvement was observed in normal-hearing listeners. CONCLUSION: Results of the present study demonstrate that companding improved speech perception in quiet and noise for ANSD listeners. The amount of improvement is higher at higher SNRs. In normal-hearing listeners, companding showed marginal improvement in both quiet and noise. The findings are discussed for rehabilitation of ANSD listeners by hearing aids which incorporate the companding strategy.

Spatial hearing in a child with auditory neuropathy spectrum disorder and bilateral cochlear implants.

OBJECTIVE: The neural dys-synchrony associated with auditory neuropathy spectrum disorder (ANSD) causes a temporal impairment that could degrade spatial hearing, particularly sound localization accuracy (SLA) and spatial release from masking (SRM). Unilateral cochlear implantation has become an accepted treatment for ANSD but treatment options for the contralateral ear remain controversial. We report spatial hearing measures in a child with ANSD before and after receiving a second cochlear implant (CI). STUDY SAMPLE: An 11-year-7-month old boy with ANSD and expressive and receptive language delay received a second CI eight years after his first implant. DESIGN: The SLA and SRM were measured four months before sequential bilateral CIs (with the contralateral ear plugged and unplugged), and after nine months using both CIs. RESULTS: Testing done before the second CI, with the first CI alone, suggested that residual hearing in the contralateral ear contributed to sound localization accuracy, but not word recognition in quiet or noise. Nine-months after receiving a second CI, SLA improved by 12.76° and SRM increased to 3.8-4.2 dB relative to pre-operative performance. Results were compared to published outcomes for children with bilateral CIs. CONCLUSIONS: The addition of a second CI in this child with ANSD improved spatial hearing.

Perception of temporally modified speech in auditory neuropathy.

OBJECTIVE: Disrupted auditory nerve activity in auditory neuropathy (AN) significantly impairs the sequential processing of auditory information, resulting in poor speech perception. This study investigated the ability of AN subjects to perceive temporally modified consonant-vowel (CV) pairs and shed light on their phonological awareness skills. DESIGN: Four Arabic CV pairs were selected: /ki/-/gi/, /to/-/do/, /si/-/sti/ and /so/-/zo/. The formant transitions in consonants and the pauses between CV pairs were prolonged. Rhyming, segmentation and blending skills were tested using words at a natural rate of speech and with prolongation of the speech stream. STUDY SAMPLE: Fourteen adult AN subjects were compared to a matched group of cochlear-impaired patients in their perception of acoustically processed speech. RESULTS: The AN group distinguished the CV pairs at a low speech rate, in particular with modification of the consonant duration. Phonological awareness skills deteriorated in adult AN subjects but improved with prolongation of the speech inter-syllabic time interval. CONCLUSIONS: A rehabilitation program for AN should consider temporal modification of speech, training for auditory temporal processing and the use of devices with innovative signal processing schemes. Verbal modifications as well as visual imaging appear to be promising compensatory strategies for remediating the affected phonological processing skills.

Brainstem electronic implants for bilateral anacusis following surgical removal of cerebello pontine angle lesions.

The multichannel auditory brainstem implant (ABI) has been used successfully to treat deafness in individuals with neurofibromatosis type II. The device has been implanted in nearly 150 recipients worldwide, and clinical trials with the device are approaching completion. The implantation and fitting of the multichannel ABI differ significantly from cochlear implantation, and the processes are illustrated in a series of case studies. Performance data also are included from recipients with up to 7 years experience.