# L 17 The Human Voice. The Vocal Tract epiglottis.

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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 f n =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

Pure 250 Hz source (with lots of harmonics) 1 kHz 2 kHz3 kHz

send that 250 Hz sound (with lots of harmonics) through the cone: 1 kHz 2 kHz3 kHz "Formant"

send that 500 Hz sound (with lots of harmonics) through the cone: 1 kHz 2 kHz3 kHz SAME Formant

Formant frequencies determine vowel sounds demo with Raven Lite …

What is the frequency of the note? 1 kHz 2 kHz3 kHz a) 2 kHz b) 3.1 kHz c) 1.0 kHz d) 250 Hz

What is the frequency of first formant? 1 kHz 2 kHz3 kHz a) 2 kHz b) 3.1 kHz c) 1.0 kHz d) 250 Hz

If I sing a higher note…. 1 kHz 2 kHz3 kHz 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

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