Derived-band auditory brainstem responses: cochlear contributions determined by narrowband maskers

Abstract

Objective

The present study sought to determine the cochlear frequency regions represented by Auditory Brainstem Responses (ABRs) obtained using the high-pass noise/derived response (HP/DR) technique.

Design

Broadband noise sufficient to mask the ABR to 50 dB nHL clicks was HP filtered (96 dB/oct) at 8000, 4000, 2000, 1000 and 500 Hz. Mixed with the clicks and HP noise masker was narrowband noise. Three derived response bands, denoted by the upper and lower high-pass noise frequencies, were obtained: DR4000-2000, DR2000-1000, and DR1000-500.

Study sample

Ten adults with normal hearing, aged 19–27 years (mean age: 22.4 years), were recruited from the community.

Results

Frequencies contributing to each DR were determined from the wave V percent amplitude (or latency shift) vs narrowband masker frequency profiles (relative to a no-narrowband-noise condition). Overall, results indicate derived band centre frequencies were closer to the lower HP cut-off frequencies for DR4000-2000 and DR2000-1000, and approximately halfway between the lower HP cut-off and the geometric mean of the two HP frequencies for DR1000-500, with bandwidths of 0.5-1 octave in width.

Conclusions

These results confirm the validity of the HP/DR technique for assessing narrow cochlear regions (≤1.0 octave wide), with centre frequencies within ½-octave of the lower HP frequency.

Keywords:

• Auditory brainstem response
• derived response
• masking
• cochlear place
• frequency

Acknowledgements

Brian Schmidt provided valuable assistance with the initial pilot studies of this work. We thank Dr. Robert Burkard for his helpful feedback on drafts of this manuscript.

Ethical approval

Research Ethics Board approval was obtained from the Behavioural Research Ethics Board of the University of British Columbia prior to commencement of the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The ABR wave V latency and amplitude data set used and/or analysed in the current study are available from the corresponding author on reasonable request.

Notes

1 This level was determined from pilot studies to produce reduction of the derived-band ABR amplitude between the HP noise cutoffs without substantially altering the responses above or below the HP noise cutoffs (i.e., to just mask without overmasking).

2 A “no response” result indicates a substantial masking effect by the NBN masker. Thus, the amplitude for that condition would be expected to be very low; insertion of the waveform’s RNL for amplitude provided a reasonable and conservative estimate of amplitude for that condition (Herdman, Picton, and Stapells 2002). Nevertheless, Figure S1 and Table S2 in the Supplementary Materials (see https://tandfonline/10.1080/14992027.2023.2227342/suppl) presents the %Amplitude results with no-response results excluded; results with no-response excluded are very similar to those including no-response results shown in Figure 2 and Table 3.

3 The +2-ms latency shift for no-response results was only used to estimate the zero-crossing frequency. Mean latency-shift results shown in Figure 2(b) do not include this +2-ms latency shift.

4 The mean (SD) wave V latencies and V-V’ amplitudes obtained for non-masked (i.e., no NBN) derived responses are presented in the Supplementary Materials section, Table S1 (see https://tandfonline/10.1080/14992027.2023.2227342/suppl).

5 As a check of the þ2-ms estimate, mean zero-crossing frequency results were also calculated using a smaller shift (þ1 ms); the mean zero-crossing frequency results using the þ1-ms shift were within 7-10 Hz of those calculated using the þ2-ms shift. Table S2 in the Supplementary Materials section (https://tandfonline/10.1080/14992027.2023.2227342/suppl) presents the results of the analysis using the þ1-ms latency shift substitution for no response.

5 As a check of the +2-ms estimate, mean zero-crossing frequency results were also calculated using a smaller shift (+1 ms); the mean zero-crossing frequency results using the +1-ms shift were within 7-10 Hz of those calculated using the +2-ms shift. Table S2 in the Supplementary Materials section (https://tandfonline/10.1080/14992027.2023.2227342/suppl) presents the results of the analysis using the +1-ms latency shift substitution for no response.

Additional information

Funding

Work supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada Discovery Grant [#183923].