ASA 127th Meeting M.I.T. 1994 June 6-10

5aBV9. Tactile and auditory measures of modulation resolution.

W. M. Rabinowitz

C. M. Reed

L. A. Delhorne

Res. Lab. of Electron., MIT, Rm. 36-789, Cambridge, MA 02139

J. M. Besing

Louisiana State Univ., Baton Rouge, LA 70803

Limited signals derived from speech can provide effective supplements to speechreading. For a single-band speech envelope that is used to modulate a 200-Hz tone, the benefit to speechreading is, however, greater with auditory than tactile presentation. Is this due to differences between hearing and touch in the psychophysical ability to perceive amplitude modulation changes? Experiments are being conducted to assess amplitude modulation discrimination as a function of reference modulation depth (m=0 to 1) and modulation frequency (f[sub m]=5 or 50 Hz). Carrier frequency is fixed at 200 Hz and stimulus presentation is via headphone for audition and a minishaker for taction. Preliminary results indicate that, on average, auditory thresholds for (Delta)m are roughly 6 dB more sensitive than tactile thresholds. These results extend those previously available in the literature by considering cases of nonzero reference values for m, which may be particularly relevant to the information that is conveyed in the single-band speech envelope. [Work supported by NIDCD.]