Changes to Low-frequency Components of the TEOAE Following Acoustic Trauma to the Base of the Cochlea

Several studies have shown that acoustic trauma to the base of the cochlea can result in loss of transient-evoked otoacoustic emission (TEOAE) energy at frequencies much lower than those affected in the audiogram. We have extended these studies to show that the low-frequency emission energy was substantially affected if the transient stimulus included frequencies within the range affected by the trauma, otherwise the change observed was small. In keeping with the suggestion that TEOAEs are predominantly comprised of intermodulation distortion energy (Yates and Withnell, Hear. Res. 136 (1999) 49-64), trauma to the basal region of the cochlea was found to affect emission energy across a broad frequency range in response to a wide-band acoustic stimulus. Further, group delay measurements demonstrated that the dominant contribution to the TEOAE originated from the basal region of the cochlea.