An investigation of the effects of temporal windowing on toneburst-evoked auditory brainstem responses in normal hearing adults

Abstract

Toneburst-Evoked Auditory Brainstem Responses (ABRs) were recorded on 20 normal hearing young adults to determine the effects of temporal windowing on the response properties of the ABR recorded at stimulus intensities ranging from 80 to 15 dB nHL.

These ABRs were recorded to 2000 Hz linear-gated tonebursts and 2000 Hz Blackman-gated tonebursts at each stimulus intensity. Testing for each subject included behavioral pure-tone audiometry from 250-8000 Hz, as well as acoustic immittance testing, including tympanometry and ipsilateral acoustic reflex testing. ABRs were recorded to both types of temporal windowed stimuli bilaterally. Testing began at 80 dB nHL and the intensity of stimuli was decreased in 10 dB increments until an intensity of 30 dB nHL was reached; at which point, intensity was decreased in 5 dB steps until the participants’ ABR thresholds were determined. This study examined various response measurements, including the absolute latencies of waves I, III, and V and the peak-to-peak amplitudes of waves I-I’ and V-V’. The results for the linear-gated 2000 Hz toneburst ABRs were compared directly to the results for the Blackman-gated 2000 Hz toneburst ABRs to determine if there were any significant differences in these response measurements.

The results of the current study revealed that as stimulus intensity decreased, the mean latency values increased for waves I, III, and V for both temporal windowed ABRs. Additionally, as stimulus intensity decreased, the peak-to-peak amplitude decreased for wave I-I’ and V-V’ for the responses to both temporal windowed stimuli. Results revealed that the ABRs recorded to the Blackman-gated tonebursts had significantly longer mean wave V latency values than the ABRs recorded to the linear-gated tonebursts. This pattern was true at all stimulus intensities, with the exception of 20 and 15 dB nHL. Additionally, there were no significant differences in the peak-to-peak amplitude values for wave V-V’ for the responses recorded to the two types of temporal windowed stimuli. This finding was true for all stimulus intensities, with the exception of 40 and 50 dB nHL. Furthermore, the mean ABR thresholds were essentially the same for both the linear-gated and Blackman-gated tonebursts.

In lieu of the current findings as well as the recent literature on this topic, it is recommended that clinicians employ Blackman-gated tonebursts if they are recording ABRs to nonmasked-toneburst stimuli to achieve better frequency specificity when estimating behavioral thresholds. The ABR data from the current study will be used to develop a parametric approach to generating simulated responses for a commercially available simulator device (i.e., Baby Isao manufactured by Intelligent Hearing Systems). Future research is needed to determine the effects of other testing parameters, including the use of other stimulus frequencies and other types of temporal windowed tonebursts on the response measurements of the ABR.