How does the vocoder work?
First, this is a channel vocoder, not a phase vocoder. Phase vocoders are used to pitch shift and time scale, and work differently. For a channel vocoder, the basic algorithm works like this: • Split the modulator (formant) and carrier into frequency bands • For each frequency band: • Find the volume of the modulator band and modulate the carrier band with that volume • Mix the bands back together to form the output That’s all there is to it, really. Of course there are plenty of different ways to implement this. Most hardware and software vocoders use a series of band pass filters, envelope followers, and modulators to achieve the result. My vocoder takes a different approach. It takes an FFT of the input signals, performs all its work in the frequency domain, and then does an inverse-FFT. If you’re still confused, this site has a good explanation. Copyright 1995-2009 Emanuel Borsboom. All content on this site is licensed under a Creative Commons License, unless otherwise specified.
