Figure 2. The Soundgin Windows
control panel provides a graphical
interface for programming and
experimenting with the Soundgin chip.
Example of amplitude patching:
Oscillator 1 produces a steady 1,000 Hz
tone. Oscillator 2 produces a slow 1 Hz
tone, which would ordinarily be below
the range of human hearing. By
patching the output of Oscillator 2 into
Oscillator 1, the output changes in volume once a second. It creates a phasing effect that sounds like something
out of an old science fiction movie.
Example of frequency patching:
Oscillator 1 again produces a standard
1,000 Hz tone. Oscillator 2 produces a
slow 1 Hz tone, and is patched into the
frequency modulator of Oscillator 1.
Rather than alter the volume (amplitude)
in this patching, Oscillator 3 changes the
frequency of Oscillator 1, producing a
rise-and-fall wailing siren effect.
Soundgin provides additional mixing and patching options that greatly
increase the variations in the sounds it
can produce. The options are too
numerous to mention here, but are
reviewed in the product documentation. And remember that Soundgin has
two fully independent mixers that feed
into one final output. The A and B sets
of oscillators can each produce their
own sounds, and can be mixed together to make overlay effects: a siren on
top of a warbler, for instance.
Music Generation
Music is little more than sound
that has certain qualities that we
humans find aurally pleasant. By linking
one tone to another, a musical score is
produced. Soundgin generates music
by setting its oscillators to frequency,
wave shape, and ADSR envelopes to
make piano, organ, and other instrument sounds.
As with general sound production,
the Soundgin Windows control panel can
be used to experiment with music synthesis. In the console window click the
Keyboard icon, and a 49-key keyboard
appears. Use the mouse to click any of
the keys, and its corresponding note is
played through the Soundgin chip.
Note that the keyboard uses just
one oscillator to produce the sound,
and you can select which oscillator to
use. This allows you to readily experiment with different effects. Play around
with the ADSR ramps, for example, and
you change the timber characteristics
of the notes. The sound wave buttons
similarly change the color of the tones.
Notice, for instance, that a saw tooth
wave makes the sound a lot more
“reedy,” like that from a saxophone.
By combining two or more oscillators to produce separate voices you can
create a kind of musical ensemble. The
Soundgin Windows control panel can
only play one note at a time through
one oscillator at a time, but the
Soundgin itself is capable of playing
multiple notes through multiple oscillators, giving you a polyphonic sound
and music synthesizer.
“I Am Tobor, Your
Robot!”
Using the Soundgin
Windows Control Panel
Perhaps the best way to play with
36 SERVO 01.2007
the sound making features of the
Soundgin is to use its program control
panel, which runs under the Windows
PC environment (see Figure 2). The
software can be downloaded from the
Soundgin website — see the Sources
box for additional information. The
console graphically depicts Soundgin’s
six oscillators, and shows how the
oscillators can be patched together.
You also see the ADSR envelopes and
other controls by which you can
modify the sound effects.
For a great introduction to
Soundgin and its capabilities, click on
the Presets button in the lower-right
corner. You will see a collection of 31
preset sound effects, as shown in
Figure 3, such as Space Drive, Wow,
Chopper, and Blip Chatter. Click each
one to hear what they’re like. As the
effect plays on the Soundgin, note the
action of the oscillators. (If any sound is
too loud, you can adjust the volume by
scaling down the Master Volume
Control.)
Now try combining two sound
effects together. Click Mix A beside the
Presets list, and choose a sound effect.
Click Mix B, and choose a different
sound effect. Both sounds are now
combined into the final output of the
Soundgin. Play with different combinations by selecting Mix A or Mix B, and
clicking on a new sound. You can quiet
any mix by selecting preset number 32,
which is silence.
Perhaps the most remarkable
feature of Soundgin is its ability to produced synthesized voice. Again, it’s all
done by cleverly combining the chip’s
oscillators to produce the elements of
speech. When these elements — called
phonemes — are strung together, the
sound is recognized as speech. This all
appears simple enough, but in reality
it’s quite difficult to achieve completely
