ROLE OF ACOUSTIC STRIAE IN HEARING - MECHANISM FOR ENHANCEMENT OF SOUND DETECTION IN CATS

We report the results of behavioral studies in cats conducted first, t o demonstrate the presence of a monaural mechanism for the enhancement of signal to noise; and then to examine the necessity or sufficiency of the acoustic striae for this mechanism. The results show that cats do indeed have a monaural mechanism for enhancing the detection of ton es in co-located background noise for noise levels at least as high as 60 dB SPL. The ablation-behavior results show that surgical section o f the dorsal (DAS) and most of the intermediate (IAS) striae has no me asurable effect on this mechanism. In sharp contrast, even partial sec tion of the trapezoid body results in a profound and permanent deficit and this deficit is not accounted for by hearing loss alone. It is co ncluded that the ascending and descending fibers in the dorsal and int ermediate acoustic striae are neither necessary nor sufficient for enh ancing the detection of salient sounds in a noisy environment while th e ascending or descending fibers in the ventral acoustic stria are suf ficient and probably necessary.