title: Bottom-up driven involuntary attention modulates auditory signal in noise processing.
abstract: BACKGROUND
  Auditory evoked responses can be modulated by both the sequencing and the signal-to-noise ratio of auditory stimuli. Constant sequencing as well as intense masking sounds basically lead to N1m response amplitude reduction. However, the interaction between these two factors has not been investigated so far. Here, we presented subjects tone stimuli of different frequencies, which were either concatenated in blocks of constant frequency or in blocks of randomly changing frequencies. The tones were presented either in silence or together with broad-band noises of varying levels.
  
  
  RESULTS
  In silence, tones presented with random sequencing elicited a larger N1m response than tones presented with constant sequencing. With increasing noise level, this difference decreased and even vanished in the condition where noise intensity exceeded the tone intensity by 10 dB. Furthermore, under noisy conditions, the N1m latency was shorter in the constant sequencing condition compared to the random sequencing condition.
  
  
  CONCLUSIONS
  Besides the well-known neural habituation mechanisms, bottom-up driven attention plays an important role during auditory processing in noisy environments. This bottom-up driven attention would allow us to track a certain auditory signal in noisy situations without voluntarily paying attention to the auditory modality.
authors.affiliation: Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, 48149 Münster, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Lagemann
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Okamoto
authors.forename: Henning
authors.initials: H
authors.lastname: Teismann
authors.forename: Christo
authors.initials: C
authors.lastname: Pantev
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D010470:Perceptual Masking / Q000502:physiology*; D010897:Pitch Discrimination / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult