Acoustic passaggio pedagogy for the male voice.

Awareness of interactions between the lower harmonics of the voice source and the first formant of the vocal tract, and of the passive vowel modifications that accompany them, can assist in working out a smooth transition through the passaggio of the male voice. A stable vocal tract length establishes the general location of all formants, including the higher formants that form the singer's formant cluster. Untrained males instinctively shorten the tube to preserve the strong F1/H2 acoustic coupling of voce aperta, resulting in 'yell' timbre. If tube length and shape are kept stable during pitch ascent, the yell can be avoided by allowing the second harmonic to rise above the first formant, creating the balanced timbre of voce chiusa.