Designing Sound in SuperCollider/Alarms

Fig 27.2: Alarm with two alternating tones

Note that we have separated this into multiple lines for clarity. Exercise: rewrite it as a single line - and use array expansion rather than writing "SinOsc" twice.

(
Ndef(\alarm, {
	var tone1 = SinOsc.ar(600);
	var tone2 = SinOsc.ar(800);
	// We switch between the tones using LFPulse, but soften the crossfade with the low-pass:
	var control = LPF.kr(LFPulse.kr(2), 70);
	var out = SelectX.ar(control, [tone1, tone2]);
	Pan2.ar(out * 0.1)
}).play
)

Fig 27.3: Alarm with three alternating tones

(
Ndef(\alarm, {
	var tone1 = SinOsc.ar(723);
	var tone2 = SinOsc.ar(932);
	var tone3 = SinOsc.ar(1012);
	// Stepper is perfect for stepping through the options:
	var control = LPF.kr(Stepper.kr(Impulse.kr(2), 0, 0, 2), 70);
	var out = SelectX.ar(control, [tone1, tone2, tone3]);
	Pan2.ar(out * 0.1)
}).play
)

Or we can write exactly the same thing a bit more generically using Demand units. The frequencies are simply given as an Array - change the values, or add new ones to the end:

(
Ndef(\alarm, {
	var freq, out;
	freq = Duty.kr(0.5, 0, Dseq([723, 932, 1012], inf));
	freq = LPF.kr(freq, 70);
	out = SinOsc.ar(freq);
	Pan2.ar(out * 0.1)
}).play
)

Fig 27.4: A choice of timbral settings

This using .cos and .sin to perform waveshaping - move the mouse left and right to choose from our 4 timbral options.

(
Ndef(\alarm, {
	var freq, out, operations;
	freq = Duty.kr(0.05, 0, Dseq([723, 932, 1012], inf));
	freq = LPF.kr(freq, 70);
	out = SinOsc.ar(freq);
	operations = [out, (out * pi).sin, (out * pi).cos, ((out+0.25) * pi).cos];
	out = Select.ar(MouseX.kr(0,4).poll, operations);
	Pan2.ar(out * 0.1)
}).play
)

Exercise: alter the "Duty" line so that you can have different durations for each of the notes.(Hint: you can use Dseq to specify times just as easily as to specify frequencies.)

Fig 27.7: A multi-ringer

This SynthDef is capable of a wide variety of sequences, as you'll see below:

(
SynthDef(\dsaf_multialarm, {
	|length=0.05, freqs=#[600,800,600,800], timbre=1, repeats=inf|
	var freq, out, operations;
	freq = Duty.ar(length, 0, Dseq(freqs, repeats), doneAction: 2);
	freq = LPF.ar(freq, 70);
	out = LeakDC.ar(SinOsc.ar(freq));
	out = Select.ar(timbre, [out, (out * pi).sin, (out * pi).cos, ((out+0.25) * pi).cos]);
	// NOTE: when writing a synthdef always remember the Out ugen!
	// (Handy shortcuts like Ndef and {}.play often add Out on your behalf)
	Out.ar(0, Pan2.ar(out * 0.1))
}).add;
)

...and now we can play it, using the sequences used in the book:

// happy blips
Synth(\dsaf_multialarm, [\length, 0.1, \freqs, [349, 0, 349, 0], \timbre, 1, \repeats, 1]);
// affirmative
Synth(\dsaf_multialarm, [\length, 0.1, \freqs, [238, 0, 317, 0], \timbre, 2, \repeats, 1]);
// activate
Synth(\dsaf_multialarm, [\length, 0.02, \freqs, [300, 125, 0, 0], \timbre, 2, \repeats, 10]);
// invaders?
Synth(\dsaf_multialarm, [\length, 0.03, \freqs, [360, 238, 174, 158], \timbre, 1]);
// information
Synth(\dsaf_multialarm, [\length, 0.05, \freqs, [2000, 2010, 2000, 2010], \timbre, 1, \repeats, 6]);
// message alert
Synth(\dsaf_multialarm, [\length, 0.15, \freqs, [619, 571, 365, 206], \timbre, 1, \repeats, 2]);
// finished
Synth(\dsaf_multialarm, [\length, 0.15, \freqs, [365, 571, 619, 206], \timbre, 3, \repeats, 1]);
// error code
Synth(\dsaf_multialarm, [\length, 0.01, \freqs, [1000, 0, 1000, 0], \timbre, 3, \repeats, 30]);
// wronnnnnnnnnng
(
Pbind(
	\instrument, \dsaf_multialarm,
	\freqs, [[1000, 476, 159, 0]],
	\timbre, 2,
	\repeats, 25,
	\length, Pseq([0.003, 0.005]),
	\dur, 0.5
).play
)

Exercise: work out why some of these multialarm examples don't quite sound like Andy's audio examples! ;)