A Pair of Advanced Exercises as a Register Treadmill

RESEARCH ON THE BIOMEDICAL ORIGIN of modal-falsetto registration has focused on adduction of the lower portion of the vocal folds.1 This lower adduction is controlled by the thyroarytenoid muscle, but acoustic pressures in the vocal tract can influence it.2 Register transitions can be smooth or abrupt, intentional or unintentional, or in some cases apparently nonexistent. With highly registered voices, teachers spend much studio time to And a register balance, or equalization, in critical pitch ranges. The effect of vocal tract acoustic pressures on registers is most pronounced when a source harmonic with relatively high energy passes through a formant. Of particular interest is a first, second, or third harmonic passage through one of the lower two formants (F^sub 1^ or F^sub 2^). The harmonic energy can be altered in this passage, and some instability (a pitch jump or register break) may be triggered due to sudden changes in acoustic pressures.3A pair of exercises (call them the Titze register treadmill) is designed to expose problems in register management. I do not recommend them as a practice exercise until the voice is very warmed up with semioccluded vocal tract exercises (lip trills, straw phonation, tongue trills, humming, etc.). As a diagnostic tool, however, they can be used anytime. When they are mastered without instabilities, a mixed registration is evident. In musical form, the exercises are five-note scales (up and down) with a vowel change on each note (Figure 1). The two exercises differ only in their vowel sequence, one being the low-vowel sequence /a-c-o-u-u/ and the other the high-vowel sequence /ae-e-e-I-i/. The starting note and the ending note (a fifth higher) depends on the voice classification. The male secondo passaggio or the female primo passaggio should be somewhere in the middle of the five-note pitch range for a given classification. The range shown in Figure 1 would be appropriate for a tenor or a mezzo soprano. For basses the starting pitch can be around A^sub 3^ and for sopranos around F^sub 4^.The acoustic (spectrographic) caricatures of these exercises are shown in Figure 2. Three of the dominant harmonics (F^sub 0^, 2F^sub 0^, and 3F^sub 0^) are drawn with solid lines and the lowest two formants (F^sub 1^ and F^sub 2^) are shown with dashed lines. The vowel sequence is shown on the horizontal axis. The important feature of the exercises is that, by design, there are multiple vowel-pitch combinations where formant and harmonics cross each other. In Figure 2a, the low vowel sequence, the first formant (F,) crosses 2F^sub 0^ and then F^sub 0^, provided the starting vowel /a/ is very bright (as in the Boston dialect). The second formant F^sub 2^ passes through harmonics 3F^sub 0^ and then 2F^sub 0^, provided the /u/ is speech-like and not modified for singing. All of these crossings reappear in the opposite direction on the downward scale. In Figure 2b, the high vowel sequence, the crossings for F^sub 1^ are similar to those in Figure 2a, but F^sub 2^ does not cross any harmonics. Hence, the two exercises can be used to isolate F^sub 1^ transitions alone from combined F^sub 1^ and F^sub 2^ transitions.As a diagnostic tool, the objective in the exercises is to reveal abrupt register changes, pitch jumps, or instabilities in phonation. As a practice tool, the objective is to avoid instabilities and discontinuities. …