L 17
The Human Voice
The Vocal Tract
epiglottis
Oscillator:
Air under pressure from the lungs make the
vocal folds vibrate.
Without the “resonator cavities”, the vibrations
sound like lips vibrating, or a trumpet or
trombone mouthpiece being “buzzed” (with a
central frequency when singing).
The tension in the vocal muscles control the
pitch.
Range of Frequencies for the Normal
Speaking Human Voice
Males: 70-200 Hz
Females: 140-400
(men have more dense and longer
vocal folds)
Singing voices (especially the higher
harmonics) extend the range into the
kilohertz region.
English Vowels
formants
Formants:
A range of frequencies that are enhanced.
The shape of the envelope determines what
vowel you hear!
We can model the vocal cavity as a
17cm long conical tube closed at
one end (the vocal fold end).
Hence the harmonics expected
would be
fn=n v/4(.17) = 1, 2, 3 kHz, etc.
The Q is very low due to the
softness of the cavity tissue, so the
resonances are rather broad.
Different shapes create different
formant frequencies
Vocal Formants
“had”
Pure 250 Hz source (with lots of harmonics)
1 kHz
2 kHz
3 kHz
send that 250 Hz sound (with lots of harmonics)
through the cone:
"Formant"
1 kHz
2 kHz
3 kHz
send that 500 Hz sound (with lots of harmonics)
through the cone:
SAME Formant
1 kHz
2 kHz
3 kHz
Formant frequencies determine vowel
sounds
demo with Raven Lite
…
What is the frequency of the note?
a)
b)
c)
d)
1 kHz
2 kHz
3.1 kHz
1.0 kHz
250 Hz
2 kHz
3 kHz
What is the frequency of first formant?
a)
b)
c)
d)
1 kHz
2 kHz
3.1 kHz
1.0 kHz
250 Hz
2 kHz
3 kHz
If I sing a higher note….
a) the pitch and the formants go up
b) the formants go up but the pitch stays the same
c) the pitch goes up but the formants stay the same
1 kHz
2 kHz
3 kHz
Operatic Tenor & Orchestra
Acoustic power in
formants allow
operatic singer to
be heard over
orchestra.
CT 8.3.2
Musicians refer to tremolo when the loudness
fluctuates while the pitch remains unchanged. Is
this an example of…
A: Frequency modulation.
B: Amplitude modulation.
CT 8.3.2b
Musicians refer to vibrato when the pitch is
wiggled up and down as you sing. Is this an
example of…
A: Frequency modulation.
B: Amplitude modulation.
Violinists can make “excursions”
From concert A of .2 semitones,
6 times/sec.
6 Hz -> “signal frequency”
440 Hz -> “carrier frequency”
0.2 semitones-> strength of the
modulation