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PHYS 103 lecture 29. voice acoustics. Vocal anatomy. Air flow through vocal folds produces “buzzing” (like lips). Frequency is determined by thickness (mass) men have lower pitch muscle control (stiffness). Vocal tract acts as a resonator length is fixed (15-20 cm). Vocal Spectrum.
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PHYS 103 lecture 29 voice acoustics
Vocal anatomy Air flow through vocal folds produces “buzzing” (like lips) • Frequency is determined by • thickness (mass) men have lower pitch • muscle control (stiffness) • Vocal tract acts as a resonator • length is fixed (15-20 cm)
Vocal Spectrum Sound entering the trachea is close to a pulse train ( many harmonics of nearly equal amplitude) Similar to organ reed: frequency of vocal folds is not much susceptible to feedback (vocal tract resonances) – it is determined mainly by muscular control
Vocal spectrum final sound filter vocal tract resonances + source pulse train vocal folds “buzz”
How we get vowels Recall: timbre of sound depends on the relative amplitude of harmonics pitch depends on the frequency of the fundamental Different vowels (same pitch) are essentially different timbres Resonance frequencies of vocal tract shape the spectrum -> determine timbre Resonance frequencies of the vocal tract are called formants We control the frequencies of formants by changing the shape of the vocal tract First formant typically controlled by mouth opening Second formant typically controlled by tongue position
Example spectra first formant aaa (wide open mouth) iii (mouth more closed) ooo
More examples – effect of tongue placement second formant uuuu wrwr
The spectrogram:a tool for measuring the voice spectrum amplitude frequency spectrogram frequency time