Journal of Neuroscience Methods 280 (2017) 47–53 Contents lists available at ScienceDirect Journal of Neuroscience Methods journal homepage: www.elsevier.com/locate/jneumeth Recording the human brainstem frequency-following-response in the free-field Nuno Gama a,b,* , Isabelle Peretz a,c,d , Alexandre Lehmann a,c,d,e a International Laboratory for Brain, Music and Sound Research (BRAMS www.brams.org), Outremont, QC, Canada b MRC Institute of Hearing Research, Nottingham, United Kingdom c Center for Research on Brain, Language and Music (CRBLM crblm.ca), Montreal, QC, Canada d University of Montreal, Psychology Department, Montreal, QC, Canada e Department of Otolaryngology Head & Neck Surgery, McGill University, Montreal, QC, Canada h i g h l i g h t s • A novel and reliable methodology for collecting human auditory brainstem frequency-following response (FFR) in the free field is proposed. • It is possible to collect FFRs using free field stimulation. • The FFRs collected using free and close-field stimulation are comparable in terms of the intrinsic, acoustical and reliability properties of the neural signal. a r t i c l e i n f o Article history: Received 28 November 2016 Received in revised form 24 January 2017 Accepted 25 January 2017 Available online 7 February 2017 Keywords: Speech Brainstem Spectral Agreement Intraclass Electroencephalography FFR EEG /da/ a b s t r a c t Background: 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. New method: 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. Results: 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. Comparison with existing method: 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. Conclusions: 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. Crown Copyright © 2017 Published by Elsevier B.V. All rights reserved. 1. Introduction The human auditory brainstem frequency-following response (FFR; sometimes referred to as complex ABR) is an objective and non-invasive electrophysiological measure used to investigate the * Corresponding author at: University of Nottingham, School of Medicine, Not- tingham NG72UH, United Kingdom. Tel.: +44 351965669764. E-mail address: nunomgama@gmail.com (N. Gama). brainstem’s encoding ability of spectral and temporal features of sound (Kraus and White-Schwoch, 2015; Skoe and Kraus, 2010). This technique originates from the clinically used auditory brain- stem response and is increasingly being used in hearing research (Krizman et al., 2010; e.g., Russo et al., 2004; Sinha and Basavaraj, 2010). Moreover, clinically relevant outcomes such as reading skills (Banai et al., 2009), music abilities (Lehmann et al., 2015a; Liu et al., 2015) and learning difficulties (Johnson et al., 2005; Song et al., 2008) have now been linked to subcortical auditory function using FFRs. Since the neural recording closely mimics the stimulating http://dx.doi.org/10.1016/j.jneumeth.2017.01.016 0165-0270/Crown Copyright © 2017 Published by Elsevier B.V. All rights reserved.