Vowel content influences relative pitch perception in vocal melodies: A comparison of models based on brightness vs. intrinsic pitch of vowels

Abstract

Past research involving real and synthesized instrumental timbres has found that note-to-note changes in brightness can influence perception of interval size. Changes that are congruent with changes in pitch led to an expansion, whereas changes that are incongruent lead to a contraction. In the case of singing, the brightness of individual notes (as measured by the spectral centroid) will vary as a function of vowel content. In a recent study, we investigated whether note-to-note changes in the brightness of sung notes were capable of influencing the perception of interval size. While results were consistent with past work on instrumental timbres, we were not able to completely rule out an alternative explanation concerning a perceptual correction for the intrinsic pitch of vowels (e.g., f0 of /i/ tends to be produced higher than /a/). In the present study, we created 288 unique note pairs that varied with regard to absolute change in f0 as well as vowel content. Vowels were sampled from across the vowel space, which allowed us to generate unique predictors for change in brightness (spectral centroid) and changes in intrinsic pitch (F2). Regression analyses will compare the effectiveness of competing models.