Beating Frequencies

// 1. Define SynthDefs
SynthDef(\subBass, { |freq = 55, amp = 0.3|
    var env = EnvGen.ar(Env.perc(0.01, 1, 0.2), doneAction: 2);
    var sig = SinOsc.ar(freq) * env * amp;
    Out.ar(0, sig ! 2);
}).writeDefFile;

SynthDef(\detunedSine, { |freq1 = 440, freq2 = 444, modFreq = 0.5, modDepth = 0.2, amp = 0.5|
    var mod = LFSaw.ar(modFreq) * modDepth;
    var sig1 = SinOsc.ar(freq1 + mod);
    var sig2 = SinOsc.ar(freq2 + mod);
    var beat = sig1 * sig2;
    var filtered = LPF.ar(beat, 2000);
    var env = EnvGen.ar(Env.asr(0.01, 1, 0.3), doneAction: 2);
    Out.ar(0, filtered * env * amp ! 2);
}).writeDefFile;

// 2. Build Score
Score([
    // Sub-bass drone
    [0.0, [\s_new, \subBass, 1001, 0, 0, \freq, 55, \amp, 0.3]],

    // Layered detuned sine waves with modulation
    [2.0, [\s_new, \detunedSine, 1002, 0, 0, \freq1, 440, \freq2, 444, \modFreq, 0.5, \modDepth, 0.2, \amp, 0.4]],
    [4.0, [\n_set, 1002, \freq1, 444, \freq2, 440, \modFreq, 0.7]],
    [6.0, [\n_set, 1002, \freq1, 440, \freq2, 444, \modFreq, 0.3]],
    [8.0, [\n_set, 1002, \freq1, 430, \freq2, 434, \modFreq, 0.9]],
    [10.0, [\n_set, 1002, \freq1, 434, \freq2, 430, \modFreq, 0.2]],
    [12.0, [\n_set, 1002, \freq1, 440, \freq2, 444, \modFreq, 0.5]],

    // Filter evolution
    [14.0, [\n_set, 1002, \modDepth, 0.3]],
    [16.0, [\n_set, 1002, \modDepth, 0.1]],
    [18.0, [\n_set, 1002, \modDepth, 0.4]],

    // End notes
    [43.0, [\n_set, 1001, \gate, 0]],
    [43.5, [\n_set, 1002, \gate, 0]],
    [45.0, [\c_set, 0, 0]]
]).recordNRT(
    outputFilePath: "~/output.wav".standardizePath,
    headerFormat: "WAV",
    sampleFormat: "int16",
    sampleRate: 44100,
    options: ServerOptions.new.numOutputBusChannels_(2),
    duration: 45,
    action: { 0.exit }
);