Vocal fold pulses produce harmonics falling 12 dB per octave
Evidence
The frequency spectrum of the regular pressure pulses generated by the vibrating vocal folds during speech and singing consists of all harmonics with an amplitude change on average of −12 dB per octave rise in frequency (see the illustration on the right in Figure 4.35). Thus for every doubling in frequency, equivalent to an increase of one octave, the amplitude reduces by 12 dB. The amplitudes of the first, second, fourth and eighth harmonics (which are separated by octaves) in the figure illustrate this effect. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1335
Categorization
- corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1335
- XREF: connects to: Different voice qualities result from distinct vocal fold modes; The number of harmonics audible halves with each octave rise in pitch; Timbre reduces to a weighted ratio of fundamental and resolved versus unresolved harmonics