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 HzFemales: 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:

1 kHz 2 kHz 3 kHz

"Formant"

send that 500 Hz sound (with lots of harmonics) through the cone:

1 kHz 2 kHz 3 kHz

SAME Formant

Formant frequencies determine vowel sounds

demo with Raven Lite…

What is the frequency of the note?

1 kHz 2 kHz 3 kHz

a) 2 kHzb) 3.1 kHzc) 1.0 kHzd) 250 Hz

What is the frequency of first formant?

1 kHz 2 kHz 3 kHz

a) 2 kHzb) 3.1 kHzc) 1.0 kHzd) 250 Hz

If I sing a higher note….

1 kHz 2 kHz 3 kHz

a) the pitch and the formants go upb) the formants go up but the pitch stays the samec) the pitch goes up but the formants stay the same

Operatic Tenor & Orchestra

Acoustic power informants allowoperatic singer tobe heard overorchestra.

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