This study explored two tenets of the Italian Bel Canto operatic singing technique. "Come si parla" and "aggiustamento." Articulatory changes in the lower formant vowel space of 11 spoken and sung vowels were systematically examined in six male singers. Results showed that singers influence the placement of the lowest formant frequencies in the sung vowel space using both a lowered larynx and modified vowel articulation (aggiustamento) with rising pitch, especially above 220Hz.
Bibliographic reference. Millhouse, Thomas J. / Kenny, Dianna T. (2008): "Vowel placement during operatic singing: 'come si parla' or 'aggiustamento'?", In INTERSPEECH-2008, 245-248.