Professional male singers' formant tuning strategies for the vowel /a/

Certain spectrum characteristics have been identified as important for register equalization around the male passaggio, an effect ascribed to formant tuning although descriptions of formant tuning diverge. Eight professional singers sang scales including their passaggio range on different vowels, applying two formant tuning strategies as found in (1) classical and (2) non-classical singing. Formant frequencies were measured using inverse filtering. Results revealed differences between the two strategies. For the classical formant tuning, systematic changes of formant frequencies with pitch were observed. For the highest note sung on /a/, F1 was below the second partial and F2 in the vicinity of the third. Similar spectrum characteristics were achieved by different F1 and F2 values between singers.