The Kyma Language for Sound Design, Version 4.5

Classic Vocoder
As a final step, imagine adding the outputs from all three filters together using a mixer:
Source
Noise+Buzz
LPF
BPF
HPF
LPF
BPF
HPF
105
Amp Follow
Amp Follow
Amp Follow
Now play Traditional vocoder-22 bands, which is pretty much what we have just described except that
there are 22 pairs of bandpass filters, not just three filters as shown above.
Use !Frequency to change the frequency of the buzz oscillator. !Noise crossfades between the noise
and the buzz oscillator inputs so that it is purely noise at the top and purely the buzz oscillator when it is
at zero.
!TimeConst is the same as the TimeConstant in the AmplitudeFollower of the previous example. It
controls how quickly the 22 amplitude followers will respond to changes in the filters’ outputs. Higher
values will give a reverberated quality, while very small values will make the speech more intelligible.
!Bandwidth is a control on the bandwidths of all 22 bandpass filters. Set the !Noise fader all the way to
the top, and then gradually decrease the value of !Bandwidth, making the filters ring more and more
until they are almost pure sine waves (because that is all that can fit in such a narrow band). You may
have to boost !InLevel, the level of the noise input, for very narrow bandwidths because less of the signal
can get through when you make the pass band so narrow.
Finally, set the !Live fader all the way to one, and try speaking into the microphone. At this setting, you
control the filters with your voice.
This is an example of imposing the amplitude and spectral content of human speech onto some synthetic
sources like noise or an oscillator. You can use the same concept to impose characteristics of human
speech onto the sound made by an animal or machine. For example, try out AD-mr dophin, selecting Live
when the GenericSource asks for the source. Now is your chance to tell off the smart dolphin from the
first example.
Now Add Frequency Deviation
You, the ever astute reader are no doubt asking “Aha, but what about the frequency tracking?” remembering
that the original example had a frequency tracker along with the amplitude follower. It turns out
that if you add frequency tracking within the band of each of the bandpass filters in the previous section,
you end up with the algorithm used by the LiveSpectralAnalysis Sound and the Spectral Analysis Tool
(which we will cover in depth in subsequent tutorials). The result is a set of amplitude envelopes just as
before, along with a set of corresponding frequency envelopes. Each amplitude and frequency envelope is
used to control the amplitude and frequency of a single oscillator. Then all of the oscillators are added
together for the final output.
Try playing piano man. This is an example of resynthesis using the frequency envelopes from one analysis
and the amplitude envelopes from another. More accurately, the amplitude envelopes are gradually
cross-faded from one analysis to the other.