Formant-based synthesis of singing

Rule-driven formant synthesis is a legacy technique that still has certain advantages over currently prevailing methods. The
memory footprint is small and the flexibility is high. Using a
modular, interactive synthesis engine, it is easy to test the
perceptual effect of different source waveform and formant
filter configurations. The rule system allows the investigation
of how different styles and singer voices are represented in
the low-level acoustic features, without changing the score. It
remains difficult to achieve natural-sounding consonants and
to integrate the higher abstraction levels of musical
Index Terms: formant synthesis, singing

Sten Ternström, Johan Sundberg

Synth Secrets, Part 23: Formant Synthesis


“ee” leap 270 2300 3000

“oo” loop 300 870 2250

“i” lip 400 2000 2550

“e” let 530 1850 2500

“u” lug 640 1200 2400

“a” lap 660 1700 2400

Finally, let’s take a look at how the FS1R imitates the frequency response of a harmonically rich signal (or noise) passed through a resonant low-pass analogue filter (see Figure 16, above right). Yes, yes… we’ve seen it all before, but bear with me one more time.

Surprisingly, we can reconstruct this frequency response using just two formants — one with a centre frequency of 0Hz and a Q of, say 0.1, and one with a centre frequency equal to the analogue filter’s Fc, and with a Q of, say, 10 (see Figure 17, right).

The result is remarkable. What’s more, we can make the formant-generated sound respond very similarly to the analogue case. To be specific, we can shift the perceived cutoff frequency by moving the centre frequency of the upper formant while narrowing the Q of the lower formant by an appropriate amount. Do this in real time, and you have a sweepable filter. Furthermore, we can increase and decrease the perceived resonance by increasing or decreasing the amplitude of the upper formant alone.

via Synth Secrets, Part 23: Formant Synthesis

Formant Vowel frequencies – Wikipedia

Formant – Wikipedia, the free encyclopedia.

Good overview and excellent reference for common f1, f2 frequencies used in forming Vowel formants. Should come in handy (when I eventually get to this feature).

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

Vowel formants

Vowel Main formant region
u 200–400 Hz
o 400–600 Hz
a 800–1200 Hz
e 400–600 and 2200–2600 Hz
i 200–400 and 3000–3500 Hz