Dissociating contributions of talker gender and acoustic variability for spectral contrast effects in vowel categorization

Abstract

Speech categorization is influenced by spectral contrast effects (SCEs), the perceptual magnification of spectral differences between successive sounds. Through SCEs, preceding acoustic contexts can bias categorization of following sounds away from reliable spectral properties. Recent findings (Assgari & Stilp, 2015 JASA) show that SCEs in vowel categorization can be modulated by talker characteristics: a clear SCE when the preceding context was 200 sentences spoken by a single talker was diminished when the context featured 200 talkers. This result was attributed to variability in mean pitch of the preceding sentences. However, neither mean sentence pitch nor talker gender was explicitly controlled, which challenges identification of the locus of the talker effect. The current study examined whether gender and pitch variability yield separable contributions to SCEs. Listeners heard precursor sentences then categorized a target vowel from an /ɪ/ to /ɛ/ continuum. Sentences were processed to add a modest l...