The Kyma Language for Sound Design, Version 4.5

Now let’s make a transformation that depends on the start time of the Sound being transformed. The reserved
word time always contains the time offset of snd in microseconds. The reserved word
totalDuration contains the total duration of the ParameterTransformer’s immediate input; it too is
given in microseconds. Try the following Transformation:
snd frequency isNil ifFalse: [
snd frequency:
(snd frequency nn -
(3 * (time / totalDuration)) nn)].
As time progresses from zero up to the number of microseconds in the total duration, the value of (time
/ totalDuration) progresses from zero up to one. The frequency of the first note has zero half steps
subtracted from it: no change at all; however, as time goes on, each subsequent note has larger and larger
fractions of 3 half steps subtracted from its pitch.
Not only can a new parameter value depend on time and its current value, it can also depend on the values
of other parameters or combinations of parameter values. Try the following Transformation:
snd duration isNil ifFalse: [
snd frequency: snd duration inverse * 100].
This transformation sets the Frequency to 100 times the inverse of whatever the Duration happens to
be.
Next, open the Sound file ParameterTransformer from the Advanced folder. Try playing the Sound
independent partials; when it asks for a frequency, enter 100 hz. Inspect independent partials; by double-clicking
on it and looking at the Frequency field of each Oscillator. The first Oscillator’s frequency
is ?frequency, the second one is ?frequency * 2, the third is ?frequency * 3, etc. When you play
independent partials, it sounds like a single, harmonic tone.
Edit the Sound called transformIndependentPartials by double-clicking on it. The Transformation
parameter has a long comment, after which it should read:
snd frequency isNil ifFalse: [
snd frequency:
snd frequency nn + (110.0 hz * time / totalDuration)].
Reading this, we would expect that each repetition of independent partials will be at a higher frequency.
When you play transform independent partials you hear, as expected, the frequencies getting higher with
each repetition. What you may not have expected is that the sound starts out harmonic and becomes inharmonic
with subsequent repetitions. Why is that?
The sequence of events is:
1. Kyma sets the Oscillator frequencies to 100 hz, 200 hz, etc.
2. The ParameterTransformer adds a multiple of 110 hz to each repetition of independent partials.
Since it adds a fixed amount to each frequency, the harmonic relationship is no longer maintained. For
example, if you start out with 100, 200, and 300 hz and then you add 110 to each frequency, the result is:
210, 310, and 410 hz. Since 410 hz is not a multiple of the lowest frequency, 210 hz, it is not a harmonic of
210 hz.
Is it possible to transform the frequencies in such a way as to maintain the harmonic relationship? One
way would be to multiply the frequencies by a constant rather than adding a constant value to them. Another
way is to create a new Sound class that maintains the harmonic relationship no matter what.
Select independent partials in the Sound file window and choose New class from example from the Action
menu. When Kyma asks for a value for ?frequency, enter 100 hz. Change the name of the new
class from newClassFromExample to HarmonicPartials. Then uncheck Expand; this tells the
Sound: Apply the transformation to yourself before you expand. If you leave Expand checked, then the
Sound will expand first and then apply the transformation to the expanded version of itself.
Close the class editor and answer that you want to save an instance of the new class; you should see a
new Sound called HarmonicPartials in your Sound file window. In the open Sound editor, replace inde-
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