Comparison of ABR stimuli for the early detection of ototoxicity: conventional clicks compared with high frequency clicks and single frequency tonebursts.

Effective objective testing methodology is needed for early detection of the effects of ototoxicity on hearing in patients. The requirements for such testing include responses that are: 1) reliable across test sessions; 2) sensitive to ototoxic change ( > 8 kHz), and 3) recordable in a time-efficient manner. Auditory brainstem responses (ABR) appear well suited to this task however, conventional clicks stimulate primarily mid-frequencies (1-4 kHz) and high frequency tonebursts require too much time. We hypothesized that delivery of a band of high frequencies (a high frequency "click"), would elicit reliable and useful ABRs. In the current study, flat and sloped HF (high frequency) clicks with a bandwidth of 8-14 kHz were used. The purpose was to compare brainstem responses elicited by tonebursts, two HF clicks and conventional clicks. The results show that the reliability of responses to the HF clicks were comparable to the tonebursts and further, both HF clicks produced responses slightly larger than tonebursts.