title: Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.forename: Ingyu
authors.initials: I
authors.lastname: Chun
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Billings
authors.forename: Christi W
authors.initials: CW
authors.lastname: Miller
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Tremblay
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D005072:Evoked Potentials, Auditory; D005260:Female; D064368:Healthy Volunteers; D006310:Hearing Aids; D006801:Humans; D008297:Male; D009622:Noise; D059629:Signal-To-Noise Ratio; D055815:Young Adult