title: Recording the human brainstem frequency-following-response in the free-field.
abstract: The human auditory brainstem frequency-following response (FFR) is an objective measure used to investigate the brainstem's encoding ability of sounds. Traditionally, FFRs are recorded under close-field conditions (earphones), but free-field stimulations (loudspeaker) have yet to be attempted, which would increase the applications of FFRs by making this technique accessible to those who cannot wear inserted transducers. Here we test the feasibility and reliability of measuring speech ABRs across free and close-field.
  
  
  
  The FFR was evoked by a 40-ms consonant-vowel (cv) /da/ syllable which was presented in the standard close-field conditions with insert earphones, and in a novel free-field condition via a loudspeaker.
  
  
  
  A well-defined FFR was observed for each stimulating method (free or close-field). We show that it is possible and reliable to elicit FFRs from a speaker and that these do not systematically differ from those elicited by conventional earphones.
  
  
  
  Neural responses were subjected to a comparative within-subjects analysis, using standard measures found in the literature in order to quantify and compare the intrinsic (amplitude, noise, consistency), acoustic (latency, spectral amplitude) and reliability properties (intraclass correlation coefficients and Bland and Altman limits of agreement) of the neural signal.
  
  
  
  Reliable FFRs can be elicited using free-field presentation with comparable to acoustical, intrinsic and reliability properties as those elicited by standard close-field presentations.
authors.affiliation: International Laboratory for Brain, Music and Sound Research (BRAMS www.brams.org), Outremont, QC, Canada; MRC Institute of Hearing Research, Nottingham, United Kingdom. Electronic address: nunomgama@gmail.com.
authors.forename: Nuno
authors.initials: N
authors.lastname: Gama
authors.affiliation: International Laboratory for Brain, Music and Sound Research (BRAMS www.brams.org), Outremont, QC, Canada; Center for Research on Brain, Language and Music (CRBLM crblm.ca), Montreal, QC, Canada; University of Montreal, Psychology Department, Montreal, QC, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Peretz
authors.affiliation: International Laboratory for Brain, Music and Sound Research (BRAMS www.brams.org), Outremont, QC, Canada; Center for Research on Brain, Language and Music (CRBLM crblm.ca), Montreal, QC, Canada; University of Montreal, Psychology Department, Montreal, QC, Canada; Department of Otolaryngology Head & Neck Surgery, McGill University, Montreal, QC, Canada.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lehmann
mesh_terms: D000161:Acoustic Stimulation / Q000295:instrumentation / Q000379:methods*; D000328:Adult; D001933:Brain Stem / Q000502:physiology*; D004569:Electroencephalography; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D005583:Fourier Analysis; D006320:Hearing Tests; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D015203:Reproducibility of Results; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult
keywords: /da/; Agreement; Brainstem; EEG; Electroencephalography; FFR; Intraclass; Spectral; Speech