title: Sensitivity of offset and onset cortical auditory evoked potentials to signals in noise.
abstract: OBJECTIVE
  The purpose of this study was to determine the effects of SNR and signal level on the offset response of the cortical auditory evoked potential (CAEP). Successful listening often depends on how well the auditory system can extract target signals from competing background noise. Both signal onsets and offsets are encoded neurally and contribute to successful listening in noise. Neural onset responses to signals in noise demonstrate a strong sensitivity to signal-to-noise ratio (SNR) rather than signal level; however, the sensitivity of neural offset responses to these cues is not known.
  
  
  METHODS
  We analyzed the offset response from two previously published datasets for which only the onset response was reported. For both datasets, CAEPs were recorded from young normal-hearing adults in response to a 1000-Hz tone. For the first dataset, tones were presented at seven different signal levels without background noise, while the second dataset varied both signal level and SNR.
  
  
  RESULTS
  Offset responses demonstrated sensitivity to absolute signal level in quiet, SNR, and to absolute signal level in noise.
  
  
  CONCLUSIONS
  Offset sensitivity to signal level when presented in noise contrasts with previously published onset results.
  
  
  CONCLUSIONS
  This sensitivity suggests a potential clinical measure of cortical encoding of signal level in noise.
authors.affiliation: National Center for Rehabilitative Auditory Research, Portland Veterans Affairs Medical Center, Portland, OR, USA.
authors.forename: Lucas S
authors.initials: LS
authors.lastname: Baltzell
authors.affiliation: National Center for Rehabilitative Auditory Research, Portland Veterans Affairs Medical Center, Portland, OR, USA; Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Sciences University, Portland, OR, USA. Electronic address: Curtis.Billings2@va.gov.
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Billings
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D009622:Noise; D059629:Signal-To-Noise Ratio
keywords: Auditory; CAEP; ERP; Evoked; N1; N2; Offset; Onset; Potential