Understanding Filter Banks And Vocoders; Filter Banks - Moog SPECTRAVOX User Manual

UNDERSTANDING FILTER BANKS AND VOCODERS

FILTER BANKS

Electronic sounds, upon their widespread introduction into mainstream culture through the 1960s,
were initially perceived as cold, strange, and alien. The early pioneers of synthesizers, Bob Moog
among them, wanted synthesizers to not only create new sounds but also model existing acoustic
sounds. Pure electronic tones emerging from a speaker, however, were a completely new experience
to listeners, as no one had ever heard sounds that were not acoustic in nature. The electronic sounds
lacked two aspects that always accompanied any acoustic sound: the tone of the room the sound is
made in (reverb) and the tone of the resonant acoustic body itself.
The resonant fixed filter bank was created to solve the second problem—to shape the sound of an
electronic tone and simulate a resonant body, like the wooden frame of a guitar, the skin and shell of a
drum, or the physical body of a human singer. The Moog 907 Fixed Filter Bank was the essential tool in
the early Moog modular systems to shape the spectral signature of a tone and thus give an electronic
sound a simulated resonant, acoustic body. Spectravox, like the 907, contains 10 filters capable of
sculpting the spectrum of sound, but its filters have variable resonance and can be jointly shifted
through the frequency domain, greatly increasing the tonal possibilities.
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