title: Deconvolution of overlapping cortical auditory evoked potentials recorded using short stimulus onset-asynchrony ranges.
abstract: OBJECTIVE
  The first aim of this study is to validate the theoretical framework of least-squares (LS) deconvolution on experimental data. The second is to investigate the waveform morphology of the cortical auditory evoked potential (CAEP) for five stimulus onset-asynchronies (SOAs) and effects of alternating stimulus frequency in normally hearing adults.
  
  
  METHODS
  Eleven adults (19-55 years) with normal hearing were investigated using tone-burst stimuli of 500 and 2000 Hz with SOAs jittered around 150, 250, 450, and 850 ms in a paired-interval paradigm with fixed or alternating stimulus frequency.
  
  
  RESULTS
  The LS deconvolution technique disentangled the overlapping responses, which then provided the following insights. The CAEP amplitude reached a minimum value for SOAs jittered around 450 ms, in contrast with significantly larger amplitudes for SOAs jittered around 150 and 850 ms. Despite this, longer latencies of N1 and P2 consistently occurred for decreasing SOAs. Alternating stimulus frequency significantly increased the amplitude of the CAEP response and decreased latencies for SOAs jittered around 150 ms. Effects of SOAs and alternating stimuli on CAEP amplitude can be modelled using a quantitative model of latent inhibition.
  
  
  CONCLUSIONS
  LS deconvolution allows correction for cortical response overlap. The amplitude of the CAEP is sensitive to SOA and stimulus frequency alternation.
  
  
  CONCLUSIONS
  CAEPs are emerging as an important tool in the objective evaluation of hearing aid and cochlear implant fittings. Responses to closely spaced stimuli provide objective information about integration and inhibition mechanisms in the auditory cortex.
authors.affiliation: Department of Linguistics, Macquarie University, NSW, Australia; HEARing Co-operative Research Centre, Australia; National Acoustic Laboratories, NSW, Australia. Electronic address: Fabrice.Bardy@nal.gov.au.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bardy
authors.affiliation: HEARing Co-operative Research Centre, Australia; National Acoustic Laboratories, NSW, Australia.
authors.forename: Bram
authors.initials: B
authors.lastname: Van Dun
authors.affiliation: HEARing Co-operative Research Centre, Australia; National Acoustic Laboratories, NSW, Australia.
authors.forename: Harvey
authors.initials: H
authors.lastname: Dillon
authors.affiliation: Department of Linguistics, Macquarie University, NSW, Australia; HEARing Co-operative Research Centre, Australia.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: McMahon
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: Alternating stimulus frequency; Cortical auditory evoked potential; Electroencephalography; Least-squares deconvolution; Stimulus onset-asynchrony