Frequency-band importance functions for auditory and auditory-visual speech by hearing-impaired adults

Abstract

How we listen to speech appears to be fundamentally different in a number of respects when we can simultaneously see the face of the speaker while listening to his or her speech. Not only is our ability to recognize and understand speech far better when we can see as well as hear, as compared to hearing alone, but the way we hear is also different. This is evident in the patterns of activity in primary auditory cortex, which are different for auditory versus auditory-visual speech inputs, as well as data from normal-hearing subjects suggesting that auditory attention is focused on different spectral regions depending on whether visual speech cues are available. The present study examines whether frequency band-importance functions are different for auditory and auditory-visual speech recognition in a group of hearing-impaired listeners. Results show that hearing-impaired listeners perform much like normal-hearing subjects in attending to primarily low-frequency speech cues under auditory-visual conditions. In contrast, under auditory-alone conditions, hearing-impaired listeners place more importance on mid-to-high-frequency acoustic information, presumably to better recognize place of articulation cues.