ASA 125th Meeting Ottawa 1993 May

5aPP10. Phase sensitivity in psychoacoustical and physiological experiments.

S. Vranic-Sowers

Dept. of Elec. Eng., and Inst. for Syst. Res., Univ. of Maryland, College Park, MD 20742

H. Versnel

S. A. Shamma

Univ. of Maryland, College Park, MD 20742

The physiological and psychoacoustical experiments in vision [R. L. De Valois and K. K. De Valois, Spatial Vision (Oxford, New York, 1990)] indicate the existence of cortical cells that are tuned to a particular frequency of a sine wave grating. In present psychoacoustical experiments, listeners' sensitivity to changes in phase of a sinusoidal ripple (in frequency domain, 41 components) was measured for different ripple frequencies and phases. The results were interpreted on the basis of responses to the same stimuli recorded from units of the primary auditory cortex (AI) in the anaesthetized ferret. Since phase sensitivity is associated with the asymmetry (or, ratio of excitatory and inhibitory portions) of cell's response area, which varies along the isofrequency axis [Shamma et al., ``Organization of response area of ferret primary auditory cortex,'' J. Neurophysiol. (in press, 1993)], similar variations are expected for the phase sensitivity. The phase detection for any arbitrary stimuli (seen as a Fourier series) might be predicted from the corresponding results in single-ripple frequency sounds. Prediction for the spectral peak stimuli described in [Vranic-Sowers and Shamma, ``The representation of spectral profiles in the auditory system,'' J. Acoust. Soc. Am. (submitted, 1992)], is discussed. [Work supported in part by AFOSR and NRL.]