Acoustic versus perceptual accounts of speaker differentiation within anterior auditory cortex Nicolas J. Abreu Carolyn McGettigan Sophie K. Scott Institute of Cognitive Neuroscience, UCL

Background To what extent does auditory cortex show sensitivity to the perceptual differences between speakers over and above the acoustic differences? Speaker identity F0 and VTL

Design Continuous carry-over design (Aguirre 2007) [Feasible?] Investigate perceptual/acoustic effects in most efficient manner BOLD activity = mean activity + direct effect + carry-over effect of previous stim Stimuli presented in unbroken sequence Passive Listening, 1 second sound + 1 second silence, 17 speakers + 1 null Stimulus Order type 1 index 1 sequences – include self-adjacencies, each ordered pair of stimuli occurs once in each sequence e.g. (0) Carry-over Parameters of Interest Acoustic Distance & Perceptual Distance Belin et al 2003

Proposal 20 adult normal controls Single condition, 325 trials per run, 3 runs, min/run excl dummy scans Whole-brain scan, TR = 3000, TE = 30, 42 axial slices, interleaved, 64x64 resolution Parametric regressors: Carry-overs, F0, VTL, Naturalness, Gender 10 min Voice-sensitive area localizer a la Belin et al sec vocal blocks, 20 8 sec nonvocal blocks, sparse sampling, TR = 10 sec, 61 total volumes Use for subject-by-subject functionally-defined ROI Behavioral Post-test: How different are these two speakers? MDS