The Kyma Language for Sound Design, Version 4.5

Stereo Placement
If a sound source is to your right or left, it is going to reach one of your ears before it reaches the other
and by the time it reaches the second ear it will have lost energy — both because it has traveled further by
then and because your head is probably blocking some of the energy. The bigger your head is, the more
extreme the differences will be between the signal that reaches your left ear and the signal reaching your
right ear.
Amplitude vs Energy
Play the Sound Pan amplitude and use the on-screen fader or a MIDI fader to control !Pan. § Compare
that to energy pan1 and energy pan2. Do you hear a difference in the loudness or position as you pan
across the speakers?
That Space between your Ears
Now try Pan phase only. The only difference between the left and right channels is the relative delay.
There is no amplitude difference between the left and right outputs. Double-click Pan phase only to take
a look at what modules were used to construct it.
You can see that a GenericSource is being fed into two different delays. Then the delays are fed into a
ChannelJoiner: one into the left input of the ChannelJoiner, the other into the right input. A ChannelJoiner
creates a stereo pair out of two inputs: the left channel of the one is routed entirely to the left
side of the stereo pair, the right channel of the other is routed entirely to the right side of the stereo pair.
(Since the right and left channels of the delay output are the same, it is immaterial which channel is read
by the ChannelJoiner in this particular instance).
Double-click on the Sound called RIGHT. Its Delay parameter specifies the maximum delay; DelayScale
determines how much of that maximum delay time you want at any given moment. The
strange message normCos stands for normalized cosine. Since so many expressions involving cosine include
a factor of π, that is automatically added when you ask for the normCos. In other words
x normCos = (Float pi * x) cos
So the expression
(0.5 * !Pan) normCos
yields the following delays for the right and left channels relative to the value of !Pan:
!Pan (0.5 * !Pan) normCos Right Delay (0.5 * !Pan) normSin Left Delay
0 1 800 usec 0 0 usec
0.5 0.5 sqrt 565.6 usec 0.5 sqrt 565.6 usec
1 0 0 usec 1 800 usec
The only thing that you really hear is the difference between the two delays, so the effective interaural
difference is 800 microseconds at the two extremes and zero when the sound source is directly in front of
you (since it takes the same amount of time to get to both ears).
Do a side-by-side (i.e. one-after-another) comparison of pan (phase & energy) against energy pan1. What,
if any, effect does adding phase delays add to the pan?
By the way, if you are interested in where the numbers come from, you can find papers on “interaural
time differences” in the Journal of the Acoustical Society of America that explain how they come up with
these time differences based on the diameter of a typical head, the speed of sound, and the assumption
that the sound source is far enough away that you can consider lines drawn from the source to the two
ears to be parallel.
168