Doepfer A-127 Triple VC Resonance Filter - Manual (Page 9)

doepfer System A - 100 Triple VC Resonance Filter A-127
9
fig. 4: German vowel formant frequency range.
In the patch in fig. 5, this process is simulated by two
of the A-127’s band-pass filters, with the sawtooth
output from a VCO acting as the sound source. An
A-155 sequencer controls the A-127. Pitch is control-
led by a keyboard.
The resonance of both of the band-pass filters should
be set quite high. The sounds from this patch will be
more realistic if the individual sounds slide from one to
the next (using the Glide Control on the A-155).
P It’s also possible to use non-harmonic
sound spectra (e.g. ring modulator signals)
for further experimentation.
Another source for discovering the formant frequency
range of English language vowel sounds is Allen
Strange's book Electronic Music. Here, he specifies
three centre frequencies for the formants for each of
the vowel sounds (see Table 1).
Tab. 1: Band-pass filter frequencies 1 to 3 for the
production of male vowel sounds (from: Allen
Strange, "Electronic Music")
If you’re trying out the patch in fig. 5, then just use the
first two frequency settings in each set of three.
Band ee i e ae ah aw u oo A er
1 270 390 530 660 730 570 440 300 640 490
2 1990 1840 1720 1090 1840 1020 870 1190 1350 -
3 3010 2550 2480 2410 2440 2410 2240 2240 2390 1690
0.2 0.4 0.6 1.2 1.8 2.6 5.0 0.8
u o a a o u a e i
f
[kHz]
+ u + o
+ o
+ u
+ a