On the frequency regions governing overshoot

Abstract

Detectability of a brief, high‐frequency tone can improve as the onset of that tone is delayed relative to the onset of a long‐duration, broadband noise masker. This effect, known as overshoot, is, in part, consistent with adaptation at the auditory nerve, although recent psychophysical experiments suggest that other mechanisms also may be involved. To gain more insight into the mechanisms underlying overshoot, several experiments were designed primarily to manipulate the spectral properties of a 200‐ms noise precursor (N0 = 20 dB SPL) whose offset preceded the onset of a 400‐ms noise masker (N0 = 20 dB SPL) by 1 ms. Depending upon its spectral composition, the precursor could reduce or eliminate overshoot by reducing threshold near masker onset. The assumption here is that the frequency regions of the precursor that reduce overshoot are those that are, in turn, responsible for overshoot. The results indicate that overshoot is governed by a relatively large frequency region that is clearly not confined to the 4.0‐kHz signal frequency region, and that frequency regions above the signal are more important for overshoot than are frequency regions below the signal. [Work supported by NIDCD.]