Vocal & Choir sounds

To simulate singing voices, you first need to take a (grossly oversimplified) look at the human sound reproduction stages.

We have:

• some envelopes + control signals (the brain)
• noise (air from the lungs)
• an oscillator (vocal chords)
• a few resonators/filters (all the cavities)
• an output (mouth)

The filters will need to be tuned to frequencies that our brain recognizes as official formants:

formant frequency

Vowel	f1	f2
u	320 Hz	800 Hz
o	500 Hz	1000 Hz
ɑ	700 Hz	1150 Hz
a	1000 Hz	1400 Hz
ø	500 Hz	1500 Hz
y	320 Hz	1650 Hz
ɛ	700 Hz	1800 Hz
e	500 Hz	2300 Hz
i	320 Hz	2500 Hz

copied from: formant frequencies on wikipedia