Spatial frequency requirements for audiovisual speech perception.
Spatial frequency band-pass and low-pass filtered images of a talker were used in an audiovisual speech-in-noise task. Three experiments tested subjects' use of information contained in the different filter bands with center frequencies ranging from 2.7 to 44.1 cycles/face (c/face). Experiment 1 demonstrated that information from a broad range of spatial frequencies enhanced auditory intelligibility. The frequency bands differed in the degree of enhancement, with a peak being observed in a mid-range band (11-c/face center frequency). Experiment 2 showed that this pattern was not influenced by viewing distance and, thus, that the results are best interpreted in object spatial frequency, rather than in retinal coordinates. Experiment 3 showed that low-pass filtered images could produce a performance equivalent to that produced by unfiltered images. These experiments are consistent with the hypothesis that high spatial resolution information is not necessary for audiovisual speech perception and that a limited range of spatial frequency spectrum is sufficient.
Munhall
K G
KG
Department of Psychology, Queen's University, Kingston, Ontario, Canada. munhallk@psyc.queensu.ca
Kroos
C
C
Jozan
G
G
Vatikiotis-Bateson
E
E
D005145:Face; D006801:Humans; D010865:Pilot Projects; D013028:Space Perception; D013067:Speech Perception; D014796:Visual Perception