Formant tracking to harmonics boosts loudness, not intelligibility, in soprano singing

Evidence

Another commonly known phenomenon is that trained soprano singers may produce such high pitches that the harmonics are sparse in frequency, so that the formant structure is not present in the signal. This makes high-pitched vocals unintelligible. Some female singers are also able to change the frequencies of the formants to match those of the harmonics of the note (Sundberg, 1977). This does not make the vocals more intelligible, but it raises the total level of sound, which might be desirable, for example, in opera singing. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 631

Categorization

• XREF: Connects with the ADDENDUM article on opera/music themes and generally to formant theory from earlier in the book’s voice chapters. — connects to: Vocal transmission distance depends more on singing height than frequency — Almo Farina, Soundscape Ecology: Principles,…, 424; A tenor’s singer’s formant appears as boosted energy between 2.4 and 3.5 kHz. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1491
• SHARE: Nerdy vocal-acoustics tidbit for a singer or voice-science friend: sopranos tune formants to harmonics purely for volume, accepting lost intelligibility.
• QUESTION: Why is loudness worth more than intelligibility in opera specifically — is it stage convention, orchestral masking, or tradition? Worth chasing.