Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level Purpose This study investigated (a) the effect of amplification on cortical auditory evoked potentials (CAEPs) at different signal levels when signal-to-noise ratios (SNRs) were equated between unaided and aided conditions, and (b) the effect of absolute signal level on aided CAEPs when SNR was held constant. Method CAEPs ... Research Article
Research Article  |   March 01, 2016
Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level
 
Author Affiliations & Notes
  • Ingyu Chun
    University of Washington, Seattle, WA
  • Curtis J. Billings
    National Center for Rehabilitative Auditory Research, Veterans Affairs Portland Health Care System, OR
    Oregon Health & Science University, Portland
  • Christi W. Miller
    University of Washington, Seattle, WA
  • Kelly L. Tremblay
    University of Washington, Seattle, WA
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Ingyu Chun: ingyu.chun@gmail.com
  • Editor and Associate Editor: Larry Humes
    Editor and Associate Editor: Larry Humes×
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Audiologic / Aural Rehabilitation / Research Articles
Research Article   |   March 01, 2016
Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level
American Journal of Audiology, March 2016, Vol. 25, 14-24. doi:10.1044/2015_AJA-15-0029
History: Received May 19, 2015 , Revised October 19, 2015 , Accepted November 18, 2015
 
American Journal of Audiology, March 2016, Vol. 25, 14-24. doi:10.1044/2015_AJA-15-0029
History: Received May 19, 2015; Revised October 19, 2015; Accepted November 18, 2015

Purpose This study investigated (a) the effect of amplification on cortical auditory evoked potentials (CAEPs) at different signal levels when signal-to-noise ratios (SNRs) were equated between unaided and aided conditions, and (b) the effect of absolute signal level on aided CAEPs when SNR was held constant.

Method CAEPs were recorded from 13 young adults with normal hearing. A 1000-Hz pure tone was presented in unaided and aided conditions with a linear analog hearing aid. Direct audio input was used, allowing recorded hearing aid noise floor to be added to unaided conditions to equate SNRs between conditions. An additional stimulus was created through scaling the noise floor to study the effect of signal level.

Results Amplification resulted in delayed N1 and P2 peak latencies relative to the unaided condition. An effect of absolute signal level (when SNR was constant) was present for aided CAEP area measures, such that larger area measures were found at higher levels.

Conclusion Results of this study further demonstrate that factors in addition to SNR must also be considered before CAEPs can be used to clinically to measure aided thresholds.

Acknowledgment
This work was supported by National Institutes of Health (NIDCD 1R01DC012769 and P30DC004661) and the U.S. Department of Veteran Affairs (RR&D C8006W). The contents do not represent the views of the U.S. government or the Department of Veterans Affairs. The first author is currently employed by Starkey Hearing Technologies; however, this study was completed prior to employment. Thanks to Katrina McClannahan and Sarah Levy for help in CAEP acquisition and Brandon Madsen and Tina Penman for help with CAEP analysis.
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