Figure 3. Three different uses of vocal tract resonances are shown here.

(a) Shows resonance tuning by sopranos. At low frequencies, the first resonance R1 is different for each vowel. As f₀ approaches R1, however, R1 is tuned to a frequency slightly above f₀. (From Joliveau et al., 2004a.) (b) shows how saxophonists tune the vocal tract to produce the altissimo range (here for a tenor saxophone). In the normal range of the instrument, below about 700 Hz, there is no simple relation between the frequencies of the note played and the tract resonance. In the high altissimo range, however, a vocal tract resonance is consistently tuned a little above the frequency of the note played—by those experienced musicians who can play in this register. (From Chen et al., 2008a.) (c) shows how didjeridu players use resonances to produce maxima and minima in the impedance of the tract that form minima and maxima respectively in the spectral envelope of the output sound. (From Tarnopolsky et al., 2006.)