formant, singing, vowel equalization, chiaroscuro


Vowel equalization is a technique that can be used by singers to achieve a more balanced vocal resonance, or chiaroscuro, by balancing corresponding front and back vowels, which share approximate tongue heights, and also high and low vowels by means of a more neutral or centralized lingual posture. The goal of this single group study was to quantify acoustic changes in vowels following a brief training session in vowel equalization. Fifteen young adults with amateur singing experience sang a passage and sustained isolated vowels both before and after a 15 minute training session in vowel equalization. The first two formants of the target vowels /e, i, ɑ, o, u/ were measured from microphone recordings. An ANOVA was used to test for changes in formant values following the training session. These formant values mostly changed in a manner reflective of a more central tongue posture. For the sustained vowels, all formant changes suggested a more neutral tongue position following the training session. The vowels in the singing passage mostly changed in the expected direction, with exceptions possibly attributable to coarticulation. The changes in the vowel formants indicated that even a brief training session can result in significant changes in vowel acoustics. Further work to explore the perceptual consequences of vowel equalization is warranted.

Original Publication Citation

Dromey, C., Heaton, E. & Hopkin, J.A. (2011). The acoustic effects of vowel equalization training in singers. Journal of Voice, 25, 678-682.

Document Type

Peer-Reviewed Article

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Permanent URL






David O. McKay School of Education


Communication Disorders