Rise-fall times and center frequency effects on auditory brainstem response to tone bursts in persons with normal hearing and simulated hearing loss

Frequency specific threshold estimation is commonly employed in the early assessment of auditory function for infants and young children and primarily used to predict behavioral thresholds, determine audiogram configuration and assist in hearing aid fitting. As these measures are of great clinical utility it is important to determine the most effective and efficient signal that provides the most accurate reflection of auditory function while ensuring response frequency and place specificity. The present study compared the effects of stimulus envelope on auditory brainstem response (ABR) to tone burst stimuli in subjects with normal hearing and a simulated moderate high-frequency notched hearing loss. ABR threshold, latency and amplitude were determined for fifteen female participants with 500 Hz and 4000 Hz tone bursts using the following stimulus rise-fall times: Blackman two-cycle rise-fall with no plateau (2-0-2), Blackman one-cycle rise-fall with no plateau (1-0-1) and constant total duration of 4 ms. Results from both the normal and hearing loss conditions suggest that differences in tone burst rise-fall times had little or no effect on ABR threshold for both stimulus frequencies. For 500 Hz and 4000 Hz tone bursts, increased stimulus duration yielded prolonged latency and reduced amplitude of Wave V as compared to shorter duration stimulus envelopes. In conclusion, the present study yielded significant differences in Wave V latency and amplitude across the three rise-fall times indicating longer stimulus durations elicit more effective and efficient test signals for both low and high frequency tone burst stimuli.