A computational study of the effect of formant tuning on vocal intensity

Formant tuning refers to matching one of the lower vocal tract resonances to a harmonic of the voice source to maximize the radiated vocal intensity. While it is often observed in sopranos singing at high notes, there have been conflicting reports for its use in male voices. Formant tuning can have large impact on vocal intensity at high pitches, where the harmonics are far apart and their amplitudes are sensitive to frequency spacing between the harmonic and the nearest vocal tract resonance, whereas at low pitches it may become less effective. In this study, the effect of formant tuning on vocal intensity is investigated in computational simulations with parametric variations in both the vocal fold and vocal tract properties. The effect of formant tuning is quantified by the difference between the A-weighted radiated sound pressure level (SPL) and the source SPL. The results showed that formant tuning significantly increases SPL at high pitches but has only small effect at low pitches. With sufficient formant tuning, the radiated SPL also increases with increasing pitch, indicating that formant tuning is more effective in increasing SPL when vocal tract resonance is tuned to a lower harmonic.