The Kyma Language for Sound Design, Version 4.5

Time Scaling
This section is the dual of Frequency Scaling on page 124; you cannot change the duration of a disk track
or sample without also changing its frequency and vice versa. For example, try playing disk file rate
chipmunks & monsters and twice as long = octave lower. Not only does changing the rate also change
the frequency, it also seems to shift the formant regions up or down, giving the impression that a larger
or smaller source produced the sound (the chipmunk or monster effect).
Granular Time Stretching
Many of the same modeling techniques used in the Frequency Scaling section can also be used to scale the
duration of a recording without affecting its frequency. For example, if we assume that the sound was
produced by a train of impulses hitting a filter, we can use granular time-stretching (see for example
time-stretched virtue and time-stretched speech) which slows down the rate without affecting either the
fundamental frequency or the formant frequencies.
In sample cloud stretch dur, two SampleClouds are used to granulate a speech sample. Experiment with
different values for !Rate, !TJitter, and !GrainDur in the virtual control surface, and then open up
the Sound to see how it works.
Try playing granular time/freq antonio, triggering a repetition of the poem using MIDI key down. This
uses several TimeFrequencyScaler Sounds on the same sample ‡ but once a second randomly chooses a
new rate and a new frequency scale. Each time you trigger it from the keyboard it will choose different
rates and different frequencies. live random granular time/freq is the same idea, except that you can
choose the live input as the GenericSource and granulate the live input.
Controlling the TimeIndex of a Resynthesis
If you analyze the spectrum of a sample, you can resynthesize it using an OscillatorBank or a GAOscillators.
Unlike sample playback, an oscillator gives you independent control over duration and frequency.
The TimeIndex of a GAOscillators, SumOfSines, or REResonator resynthesis is normally a linear ramp
function that starts at -1 at the beginning, grows to 0 by the middle, and reaches a value of 1 by the end.
In rate control on GA, the TimeIndex OnDuration is set to:
2.39415 s + ((1 - !Rate) * 10)
If !Rate is 1, then the time index has its normal duration and the GA reads through its envelopes at the
normal rate. However, if !Rate is less than 1, the OnDuration is larger, and the time index takes longer
to get through the amplitude envelopes, thus increasing the duration. (Try playing this Sound and adjusting!Rate
in the virtual control surface). This technique is not without its artifacts; if you try dur
scaled FL GA, you can hear features like vibrato and tremolo slow down when you slow down the rate.
The same technique can be applied to the time index that controls the amplitude and frequency envelope
rate of a full-blown additive resynthesis using the SumOfSines or a spectral source and an Oscillator-
Bank. For example, play Kurdish dur scale § and adjust the !Rate from the virtual control surface.
tantalizing celthrpGliss uses
exp L * 100 s + 2 s
as its OnDuration. Since exp has an exponential function shape, the value of OnDuration gets larger as
time goes on. The result is a resynthesis of a harp glissando that never seems to reach the top.
In bass-keydown slows time, ‡ the OnDuration is set to
5 s + (100 * !KeyDown) s
‡ This is a fragment of a poem written and performed by composer and fellow Kyma user Antonio Barata.
§ Analysis of sample from Thomas Tibert’s New World Order sample collection.
‡ Analysis of sample from Thomas Tibert’s Methods of Mayham sample collection.
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