Effects of Hearing Aid Amplification on Robust Neural Coding of Speech

<p>Hearing aids are able to restore some hearing abilities for people with auditory impairments, but background noise remains a significant problem. Unfortunately, we know very little about how speech is encoded in the auditory system, particularly in impaired systems with prosthetic amplifiers. There is growing evidence that relative timing in the neural signals (known as spatiotemporal coding) is important for speech perception, but there is little research that relates spatiotemporal coding and hearing aid amplification.</p> <p>This research uses a combination of computational modeling and physiological experiments to characterize how hearing aids affect vowel coding in noise at the level of the auditory nerve. The results indicate that sensorineural hearing impairment degrades the temporal cues transmitted from the ear to the brain. Two hearing aid strategies (linear gain and wide dynamic-range compression) were used to amplify the acoustic signal. Although appropriate gain was shown to improve temporal coding for individual auditory nerve fibers, neither strategy improved spatiotemporal cues. Previous work has attempted to correct the relative timing by adding frequency-dependent delays to the acoustic signal (e.g., within a hearing aid). We show that, although this strategy can affect the timing of auditory nerve responses, it is unlikely to improve the relative timing as intended.</p> <p>We have shown that existing hearing aid technologies do not improve some of the neural cues that we think are important for perception, but it is important to understand these limitations. Our hope is that this knowledge can be used to develop new technologies to improve auditory perception in difficult acoustic environments.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biomedical Engineering

Year

2013

Author dc:creator

• Boley, Jonathan Daniel

Contributors dc:contributor

• Michael Heinz
• Joshua Alexander
• Edward Bartlett
• Donna Fekete
• Thomas Talavage

• biological sciences
• applied sciences
• health and environmental sciences
• auditory nerve
• hearing aid
• neural coding
• spatiotemporal
• Biomedical
• Neuroscience and Neurobiology
• Speech Pathology and Audiology

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/190

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-1024