Behavioral and Neurophysiological indices of Speech Fine Structure Processing Relevant for Speech Perception in Noise

About This Grant

PROJECT SUMMARY Speech fine structure (FS) information consists of frequency modulation cues that are vital for perceiving speech in the presence of noise. However, there is a lack of speech-based tests that can inform the processing of FS in a variety of population. Further, very little is known about how FS in speech is neurophysiologically encoded in different individuals, due to which there is also a lack of tools to objectively evaluate the neural coding of FS and effectively remediate FS processing in a variety of conditions that affect speech perception. In this study, we propose a novel and easy to use speech-based psychoacoustic and non-invasive electrophysiological (multichannel EEG) tools for assessing the perception and neural encoding of FS information in the presence of noise individuals with typical hearing and individuals with hearing loss. In Aim1, we leverage the phenomenon of temporal integration of FS in speech to parametrically assess the importance of FS information for speech perception in different types and levels of noise. Unlike non-speech stimuli, the methods developed in the study will use ecologically valid speech stimuli such that the results are generalizable to speech perception in real- world listening situations, and have the potential to characterize inter-individual differences and are applicable to wider range of hearing losses. In Aim 2, we will evaluate the the neural signatures of speech FS processing by parametrically increasing FS information in sentences. The neural signatures here will be quantified as the encoding of the speech envelope embedded on carriers with differing amount of FS, thus providing a proxy for FS processing. Our approach in retaining the envelope and modifying the FS information circumvents the problem of recovered envelopes in assessing speech FS processing. This will provide empirical evidence for the importance of FS for speech perception in noise and the metrics developed in this project will be useful to develop subjective and objective assessment tools and speech processing strategies in cochlear implants and individualizing of hearing aid fine-tuning to maximize listening outcomes. The study will further serve as the basis for further research designed to develop clinically viable psychoacoustic and electrophysiological protocols that can be easily realized in a limited test time to assay FS processing.