Role of temporal fine structure in speech recognition: From psychoacoustics to cochlear implants

Abstract

The path from fundamental research to real-world application is often long and sinuous. This presentation will depict how psychoacoustic studies performed in Sid Bacon's laboratory have engendered our original view of the role of temporal fine structure (TFS) in speech recognition, and how this view has in turn led to the development of an extremely effective speech-processing strategy for cochlear implants. First, psychoacoustic data showing how normal-hearing listeners can detect amplitude modulation when presented with only the TFS will be described. Second, a series of experiments illustrating the “absence” of acoustic speech cues in the TFS will be briefly presented. Finally, the results of a recent study involving a dual-carrier vocoder will be described. These results suggest that TFS cues are primarily used to assist in identifying which auditory channels are dominated by the target signal so that the output of these channels can be combined at a later stage to reconstruct the internal representation of that target. They also indicate that cochlear implants implementing a speech-processing strategy based on the “dual-carrier strategy” have the potential to restore nearly perfect speech intelligibility in noise. [Work supported by NIH.]