The Kyma Language for Sound Design, Version 4.5

SpectralShape
Spectral Sources Category
A SpectralShape sets the frequencies and amplitudes of oscillators in an OscillatorBank according to the
Spacing and SpectralEnvelope parameters. This kind of Sound makes sense only when used as an
Input to an OscillatorBank. Frequencies are output on the right channel and their corresponding
amplitudes are output on the left channel.
Frequency
The frequency can be specified in units of pitch or frequency. The following are all ways to specify the A
above middle C:
440 hz (in hertz or cycles per second)
4 a (as the 4th octave A)
69 nn (as a MIDI notenumber)
4 c + 9 nn (as 9 half steps above middle C)
1.0 / 0.00227273 s (inverse of a period at 44.1 kHz sample rate)
The following are examples of how to control the frequency using MIDI, the virtual control surface, or a
third-party program:
!Pitch (key number plus pitch bend)
!KeyNumber nn (MIDI notenumber)
4 c + (!Frequency * 9 nn) (continuous controller from 4 c to 4 a)
Spacing
This is the spacing between the partials and should be specified in units of frequency. To specify
harmonic partials, set the Spacing to be the same as the Frequency. For example, if you have set
Frequency to !KeyNumber nn, then setting Spacing to !KeyNumber nn will tell the OscillatorBank to
generate harmonics of !KeyNumber nn.
NbrPartials
This is the number of (amplitude,frequency) pairs that the SpectralShape will supply to an OscillatorBank.
For example, if there are 20 partials, this Sound will output the amp1 and freq1 on the first sample, amp2
and freq2 on the second sample, and on through amp20 and freq20 on the 20th sample. Then it will start
over again with amp1 and freq1.
Wavetable
The shape stored in this wavetable is interpreted as the shape of the spectrum, from 0 hz up to half the
sampling rate. An OscillatorBank can use this table to set the amplitude of each of its oscillators
according to that oscillator’s frequency. For example, if the frequency falls in a region with a low
amplitude in this table, it will be attenuated in the OscillatorBank. To see the spectral envelope, open this
file using File open with the file type set to Samples file. If the OscillatorBank waveform is Sine, and you
have chosen harmonic spacing, then this shape will be something like a filter acting on a bandlimited
pulse train (equal amplitude, harmonically spaced sine waves).
Scale
Used as an overall amplitude scale applied equally to all of the oscillators.
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