The Kyma Language for Sound Design, Version 4.5

Double-click track the pulse to see how it works:
Look at the parameter settings for trigger MIDI out when thresh exceeded. Notice that Gate is set so that
it triggers the MIDI output event each time a threshold is exceeded (we will take a close look at the
Threshold Sound in a moment), and that Frequency is set to:
(( Threshold2 L nextRandom * 6) of: #(0 2 4 7 9 12)) nn + !Pitch
In other words, each time the threshold is exceeded, it picks a new random index into an array of intervals
and adds that number of half steps the to the current pitch from the keyboard.
Now let’s take a closer look at Threshold2 (double-click on it to show its parameters). The output of this
Sound is zero except when its input exceeds the Threshold at which point the output becomes one.
Hysteresis is like inertia or a tendency for the Sound to prefer to stay in its current state of either one or
zero. To switch from zero to one, the input actually has to exceed the Threshold plus the Hysteresis;
once it is at one, it has to dip below the Threshold minus the Hysteresis before it gives up and goes
back to zero. This protects the Sound against clicking on and off rapidly if the Input is wavering just
around the Threshold.
The input to the Threshold is an AmplitudeFollower on a GenericSource which, in its default setting, is
playing back a drum loop from a sample CD called Sample Material from Sounds Good. ‡ Notice that the
AmplitudeEnvelope Sound has a parameter called TimeConstant which we have set to !Tc * 0.1 s, so
that it will be one tenth of its setting in the virtual control surface. This is a kind of responsiveness factor
or averaging time. If it is too short, the output will react to every minute change in the input and you will
just hear the original waveform; on the other hand, if it is too long, then you will lose some of the fast
transients in the input that should be reflected in the amplitude envelope.
Notice that the GenericSource is also fed through a DelayWithFeedback and into a Mixer with the output
of the synthesizer and the MIDIOutputEvent. If you look at the delay parameters, you can verify that the
GenericSource is delayed by the same amount of time as the TimeConstant in the AmplitudeEnvelope,
because an amplitude envelope follower is, by definition, a little “sluggish”, because it is ignoring instantaneous
changes in amplitude in the waveform in favor of getting an overall picture of how the
amplitude is changing over time. Delaying the original audio signal by about the same amount as the
delay introduced by the envelope follower makes the audio line up more exactly with the MIDI events
that are being triggered by the original’s amplitude envelope.
‡ Special thanks to Thomas Tibert for permission to include some of the samples from his Sounds Good collection.
Thomas (a fellow Kyma user) has an interesting ear and has gathered together an intriguing selection of sounds on
several CDs including samples of instruments from all over the world, hilarious outtakes from old documentaries,
analog synths, and excellent performances and recordings of more traditional instrument tones and loops. See his
web site for more information http://www.ivo.se/sounds.good/.
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