PB rollover and the acoustic reflex.

Abstract

We present the results of a retrospective study of the speech understanding of 52 subjects with surgically confirmed acoustic neurinoma. Subjects were divided into three groups, depending on whether acoustic reflexes were all present, all absent, or present with abnormalities in the pathological ear. Results indicated that the three groups were homogeneous with respect to pure-tone sensitivity and PBmax. Subjects who lacked all acoustic reflexes, however, experienced significantly greater rollover of speech intelligibility at high intensities than did subjects with all or some reflexes intact. A neural-mechanical interaction is suggested as a basis for the rollover phenomenon in subjects with retrocochlear eight-nerve disorder.