Question

19. If you see multiple, evenly spaced frequencies which are prominent in your hum or "ahh sound, why might that be? Think about resonance! 20. If you are able to roughly guess the three major frequencies in your voice, try to backwards calculate the length of your vocal cords. Assume that the loudest frequency is the fundamental mode, the second loudest is the first overtone, etc. You might find your result from #18 to be helpful

Answer 1

19.

Vocal tract can be modeled as a closed tube resonator. Three significant resonance frequencies (prominent peaks in the harmonic spectrum of voice) are observed at first, third and fifth harmonics.

Of course, these frequencies can be changed even further by articulators(tongue position and shape, soft pallette position, area of opening, position of jaw etc.)

Typically, vocal tract is 18 cm long corresponding to a fundamental frequency of approx 500 Hz. So resonant frequency observed are of 500 Hz, 1500 Hz and 3500 Hz.

Articulators can induce changes in these resonant frequencies. For example, the jaw opening, controls the first resonant frequency, also called first formant. If the jaw is opened wider then the first formant frequency increases.