Xuefeng Yang
D. Wesley Grantham
Bill Wilkerson Ctr. and Div. of Hear. and Speech Sci., Vanderbilt Univ. School of Medicine, 1114 19th Ave. South, Nashville, TN 37212
The precedence effect is a phenomenon that may occur when a sound from one
direction (the lead) is followed within a few milliseconds by the same or a
similar sound from another direction (the lag, or the echo). Typically the lag
sound is not heard as a separate event and the lag sound cannot be localized.
Traditionally these two aspects of precedence (echo suppression and
localization suppression) have been assumed to represent the operation of a
single mechanism. The hypothesis is proposed in this study that localization
suppression and echo suppression are at least partially independent phenomena.
A series of experiments was conducted to test this hypothesis as well as to
investigate the acoustic parameters that affect the magnitude of localization
suppression and echo suppression. In the first experiment subjects showed a
significantly greater degree of echo suppression than of localization
suppression when presented with an extended train of lead-lag noise burst
pairs. In other experiments it was shown that the magnitude of localization
suppression is affected primarily by the degree of spectral overlap of lead and
lag sounds, and to a lesser extent by the relative ``localization strength'' of
the two sounds [P. L. Divenyi,