Speechreading enhancement: a comparison of spatial-tactile display of voice fundamental frequency (F0) with auditory F0.

In two experiments, subjects repeated video-recorded sentences presented via speechreading with and without enhancement by a sensory input derived from the acoustic speech signal. Enhancement was measured as percentage increase in recognized words. In experiment 1, tactile presentation of fundamental frequency (F0) provided, after training, for three of four postlingually deafened adults a mean enhancement of 11%. In experiment 2, using six hearing adults, the auditory presentation of F0 provided a mean enhancement of 50%. This value fell, but only to 37%, when the F0 signal was derived from the processor of the tactile aid used in experiment 1. From these experiments it can be concluded that the unexpectedly small enhancement found in experiment 1 is probably due both to the fact that this tactile aid was not providing effective access to all of the information available in the F0 contour and to limitations related to the tactile processing ability of the kinaesthetic system.