Investigating The Voice

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

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.

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

Action of vocal folds

• Let’s take a look and see….

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)

• 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

Vowel sounds

• Created by changing vocal tract to place formants (typically first and second formants) at different frequencies

• See following graph

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

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

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

• 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

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