Investigating The Voice

1. Investigating The Voice

2. The voice follows the rules of physics… • The pitch of a vocal sound is affected by the air pressure in the lungs, length and tension of vocal folds • Vocal folds act like a “free reed”: the production of sound does not depend on feedback from an air column to determine the pitch • Consider the analogy of air coming out of the stretched neck of a rubber balloon

3. Vibrato • As found in Western art music (operatic style): undulation of the frequency and amplitude of partials • Thought to be achieved with both laryngeal muscles and air flow • Typical rate is 5-7 Hz.

4. Vocal Registers • The voice does not “overblow” to sing in a higher register • Female - “chest voice” is lower & fuller “head voice” is higher & lighter • Male - “chest voice” is lower & fuller “falsetto” is higher and lighter • Falsetto involves a different shape to vocal folds; perhaps not completely closing • Countertenor: male singer specializing in falsetto register

5. Action of vocal folds • Let’s take a look and see….

6. Vocal Formants • Formant: “a broad resonance region that enhances the upper harmonics lying in a fixed frequency range…” Roederer, p. 128 • Think of a formant as a type of filter which boosts certain ranges of frequencies (and reduces others) from a sound generator • Analogy to wooden box of a violin (even the same strings will sound different mounted on a different violin)

7. Vocal tract acts like an air column which is closed at one end, with a length of approx. 14 cm (female) or 17 cm (male) • An air column of 17 cm would produce a fundamental resonance around 550 Hz., with odd partials above that at 1650 Hz and 2750 Hz. (remember how waves act in a closed tube) • These resonance points are formants

8. Vowel sounds • Created by changing vocal tract to place formants (typically first and second formants) at different frequencies • See following graph

11. The vocal tract is a flexible tube… • With a wide pharynx, the larynx tube can act like a separate resonator and can be tuned to line up 3rd and 4th formants • This can produce the “singer’s formant”, with a peak around 2500-3000 Hz. • The singer’s formant is used especially by male singers and altos; the fundamental frequencies sung by sopranos make their overtones too high • Singers making the most of formants in this range can be heard over a full orchestra (!) and in large spaces

12. The singer’s formant allows the singer to be heardover the orchestra (graph from Benade, Fundamentals of Musical Acoustics)

13. Overtone Singing • Is it possible to sing more two or more notes at once??? • Listen to Artii-Sayir (“The Far Side of a Dry Riverbed”) performed by Vasili Chazir

14. Overtone singing is 2, 3, or even 4 sounds at once • Found in several cultures of inner Asia, such as Mongolia and southern Siberia • Tuvan people of the Republic of Tyva have received attention in the last 10 years • Overtone singing used to lull babies, herding, hunting, wedding celebrations

15. How is it done? • Use a tone with a low fundamental frequency (< 100 Hz.) • Manipulate shape of vocal tract to align the frequency of one or two formants (such as 1st and 2nd, or 2nd and 3rd) to a harmonic, thus enhancing it so that it is heard as a separate sound