Vowel equalization is a technique that can be used by singers to achieve a more balanced vocal tone. The technique balances corresponding front and back vowels, which share approximate tongue heights, and also balances high and low vowels in a more neutral or centralized lingual posture. Formants are resonance peaks that define each specific vowel. This study measured shifts in the first and second formants (F1 and F2) of the vowels /e, i, ɑ, o, u/ following training in vowel equalization. Prior to the training, the vowel formants were measured in amateur 15 college-aged singers. They sang the first two stanzas of “Somewhere Over the Rainbow” and then sustained each vowel for approximately 2 seconds. Following a 15-minute instruction in the vowel equalization technique, the singers repeated the exercises and the formants were re-measured. Shifts in F1 and F2 represent changes in lingual placement within the oral cavity. Vowel equalization pulls the lingual posture of a particular vowel to a more neutral or central position. While singing, a neutral placement is perceived as a pleasing balance between bright and dark tones. This study showed that following training the singers' formant values changed in a manner reflective of a more central tongue posture. These findings support the suggestion that the vowel equalization technique does indeed alter the articulation of sung vowels, shifting the formants to produce the desired chiaroscuro or balance between bright and dark sounds.



College and Department

David O. McKay School of Education; Communication Disorders



Date Submitted


Document Type





formant, singing, vowel equalization, chiaroscuro