title: Neural encoding and perception of speech signals in informational masking.
abstract: OBJECTIVE
  To investigate the contributions of energetic and informational masking to neural encoding and perception in noise, using oddball discrimination and sentence recognition tasks.
  
  
  METHODS
  P3 auditory evoked potential, behavioral discrimination, and sentence recognition data were recorded in response to speech and tonal signals presented to nine normal-hearing adults. Stimuli were presented at a signal to noise ratio of -3 dB in four background conditions: quiet, continuous noise, intermittent noise, and four-talker babble.
  
  
  RESULTS
  Responses to tonal signals were not significantly different for the three maskers. However, responses to speech signals in the four-talker babble resulted in longer P3 latencies, smaller P3 amplitudes, poorer discrimination accuracy, and longer reaction times than in any of the other conditions. Results also demonstrate significant correlations between physiological and behavioral data. As latency of the P3 increased, reaction times also increased and sentence recognition scores decreased.
  
  
  CONCLUSIONS
  The data confirm a differential effect of masker type on the P3 and behavioral responses and present evidence of interference by an informational masker to speech understanding at the level of the cortex. Results also validate the use of the P3 as a useful measure to demonstrate physiological correlates of informational masking.
authors.affiliation: National Center for Rehabilitative Auditory Research, Portland Veterans Affairs Medical Center, Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon OR 97239 , USA. keri.oconnell2@va.gov
authors.forename: Keri O'Connell
authors.initials: KO
authors.lastname: Bennett
authors.forename: Curtis J
authors.initials: CJ
authors.lastname: Billings
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Molis
authors.forename: Marjorie R
authors.initials: MR
authors.lastname: Leek
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D004192:Discrimination, Psychological / Q000502:physiology; D018913:Event-Related Potentials, P300 / Q000502:physiology; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D046709:Pattern Recognition, Physiological / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D010700:Phonetics; D011597:Psychomotor Performance; D011930:Reaction Time / Q000502:physiology; D059629:Signal-To-Noise Ratio; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult