Subjective and objective effects of the interaction between cognition and hearing aid processing on reverberant speech

This project aims to explore the effects of varying compression speeds on reverberant signals through both objective and subjective measures. Some hearing aid manufacturers include settings which claim to improve listening in reverberant environments; however, there is currently no research on the efficacy of these programs which are simply fast-acting compressors. The implication of this feature is that a fast compressor suppresses distortion of a signal introduced by a reverberant listening environment. This represents one of the first projects to investigate the interaction between compression speed of a hearing aid processor and reverberation. This interaction will be investigated via a sentence recognition task for sentences processed under a range of compression speeds and reverberation levels. Two effects of reverberation and release time on the identification of sentences will be evaluated: (1) intelligibility and (2) clarity. Including both objective and subjective measure is more sensitive assessment of the reverberation x compression speed interaction. Subjects will consist of mild to moderately-severe hearing impaired individuals. Sentences will come from the IEEE corpus and undergo hearing aid processing and reverberation simulations. Subjects will repeat back the sentences which will be scored based on 5 key words per sentence (objective measure) and indicate how clear the sentence was on a 7-point scale (subjective measure). Additionally, subjects will post hoc be divided into two groups based on their working memory capacity. An individual’s working memory is known to play a factor in determining optimal compression speeds; thus including it as a factor will give insight into how the interaction between reverberation and release time varies from individual to individual. This project’s combination of acoustics (reverberation), audiology (compression speed), and cognitive science (working memory) will provide greater insight into how to fit a hearing aid for an individual struggling with reverberation than has previously been done in the literature. Results of this study will inform clinicians in their prescription of a hearing aid for subjects who report difficulty hearing in reverberant environments, such as a church. Additionally, findings will indicate whether some patients may benefit differentially from such a reverberation-suppressing feature based on an individual’s working memory capacity. These will improve the hearing aid experience by providing specific information for individualized care.