Spectro-temporal interactions in auditory and auditory-visual speech processing

Speech recognition often involves the face-to-face communication between two or more individuals. The combined influences of auditory and visual speech information leads to a remarkably robust signal that is greatly resistant to noise, reverberation, hearing loss, and other forms of signal distortion. Studies of auditoryvisual speech processing have revealed that speech-reading interacts with audition in both the spectral and temporal domain. For example, not all speech frequencies are equal in their ability to supplement speech-reading, with low-frequency speech cues providing more benefit than high-frequency speech cues. Additionally, in contrast to auditory speech processing which integrates information across frequency over relatively short time windows (20- 40 ms), auditory-visual speech processing appears to use relatively long time windows of integration (roughly 250 ms). In this paper, some of the basic spectral and temporal interactions between auditory and visual speech channels are enumerated and discussed.