The Human Voice

1
The Human Voice

• Chapters 15 and 17

2
Main Vocal Organs

• Lungs
• Reservoir and energy source
• Larynx
• Vocal folds
• Cavities pharynx, nasal, oral
• Air exits through nasal and oral cavities

3
Larynx

• Vocal folds (not really cords)
• Glottis
• Vocal folds act on air stream
• Completely closed (stopping air and sound)
• Completely open (no soundbreathing)
• Slightly open (h sound)
• Rapid opening and closing, modulating the air
  stream)

4
Vocal Fold Vibration

• Rapid vibrations produce a buzzing sound
  Analogous to lips on a brass instrument
• Rate of vibration determined primarily by mass
  and tension (less so by air pressure and
  velocity)
• Adult males typically have longer folds with
  greate mass than females.
• Feedback from acoustic impedance has little
  effect.

5
Typical Vibration Frequencies

• 110 Hz in male
• 220 Hz in female
• 300 Hz in child
• Wide variations from one individual to another.

6
Vocal Tract

• Tube from vocal folds to lips, with side tract to
  nasal cavity.
• Length approx. 17 cm, slightly changeable by
  raising or lowering the pharynx, and by shaping
  the lips.
• Nasal cavity is approx. 12 cm, not changeable.

7
Vocal Tract (2)

• Oral Cavity most flexible
• Size and shape variable by adjusting positions of
  palate, tongue, lips, and teeth.
• Mouth opening small compared to wavelength.
• Only important in regards to resonance freq.s
• Mouth radiates more efficiently at higher fs.

8
Voice Spectrum

• The waveform can be considered either to be a
  narrow triangle wave, or a pulse wave.
• Both produce a buzzing sound, with all harmonics
  of the fundamental frequency.
• Spectrum is product of three components
• Speech sound source x filter x radiation eff.

9
ResonancesFormants

• Frequency mainly determined by vocal folds.
• Peaks in sound spectra for different vowels
• Formants
• Independent of pitch

10
Resonance Frequencies for Vowels

• Fixed formant frequencies for each vowel.
• Spoken Table 15.3, p. 346
• Sung Table 17.1, p. 378

11
Formant Tuning by Sopranos

• Changing the size of the mouth opening (lips and
  jaw) can change the tuning of formants.
• Necessary when fundamental pitch is above a
  formant.
• Also used to tune formants to match harmonics of
  fundamental pitch.
• Wider openings move formants higher in frequency.
• Vocal distortion not objectionable, except at
  very high pitch ranges.