title: Congenital amusia: a cognitive disorder limited to resolved harmonics and with no peripheral basis.
abstract: Pitch plays a fundamental role in audition, from speech and music perception to auditory scene analysis. Congenital amusia is a neurogenetic disorder that appears to affect primarily pitch and melody perception. Pitch is normally conveyed by the spectro-temporal fine structure of low harmonics, but some pitch information is available in the temporal envelope produced by the interactions of higher harmonics. Using 10 amusic subjects and 10 matched controls, we tested the hypothesis that amusics suffer exclusively from impaired processing of spectro-temporal fine structure. We also tested whether the inability of amusics to process acoustic temporal fine structure extends beyond pitch by measuring sensitivity to interaural time differences, which also rely on temporal fine structure. Further tests were carried out on basic intensity and spectral resolution. As expected, pitch perception based on spectro-temporal fine structure was impaired in amusics; however, no significant deficits were observed in amusics' ability to perceive the pitch conveyed via temporal-envelope cues. Sensitivity to interaural time differences was also not significantly different between the amusic and control groups, ruling out deficits in the peripheral coding of temporal fine structure. Finally, no significant differences in intensity or spectral resolution were found between the amusic and control groups. The results demonstrate a pitch-specific deficit in fine spectro-temporal information processing in amusia that seems unrelated to temporal or spectral coding in the auditory periphery. These results are consistent with the view that there are distinct mechanisms dedicated to processing resolved and unresolved harmonics in the general population, the former being altered in congenital amusia while the latter is spared.
authors.affiliation: International Laboratory for Brain, Music and Sound Research (BRAMS) and Center for Research on Brain, Language and Music (CRBLM), Department of Psychology, University of Montreal, C.P. 6128, succursale Centre-ville, Montreal, QC, Canada H3C 3J7. Electronic address: marion.cousineau@umontreal.ca.
authors.forename: Marion
authors.initials: M
authors.lastname: Cousineau
authors.affiliation: Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, MN 55455, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Oxenham
authors.affiliation: International Laboratory for Brain, Music and Sound Research (BRAMS) and Center for Research on Brain, Language and Music (CRBLM), Department of Psychology, University of Montreal, C.P. 6128, succursale Centre-ville, Montreal, QC, Canada H3C 3J7.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Peretz
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D001308:Auditory Perceptual Disorders / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010898:Pitch Perception; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors
keywords: Auditory filter bandwith; Auditory perception; ILD; ITD; Pitch; Spectro-temporal fine structure