Transcript The Voice - UCF Physics

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 heard
over 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