Designing Sound in SuperCollider/Rolling can

Fig 31.3: simple approximation to a drink can The four clear resonances are identified using a spectrogram of a can. ( x = { |t_trig=0| // This line just creates a sharp little spike whenever we want: var strike = EnvGen.ar(Env.perc(0.0001, 0.001, 0.1), t_trig); // here's the resonances: var son = Ringz.ar(strike, [359, 426, 1748, 3150], 0.2).sum; // some distortion livens up the spectrum a little: son = HPF.ar(son.clip2(0.6), 300); son * 0.2 }.play; ) x.set(\t_trig, 1); // Run this line to hit the can! Fig 31.6: a repeating roll pattern This simulates the regular turning of the drinks can. Since it's a control signal we'll plot it rather than play, for now. ( ~regularroll = { |rate = 1| // In the original code, Andy uses a master phase control, // wrapping and re-scaling it before differentiating, to produce // a repeating but disorderly set of impulses. // Here we do it differently - we use Impulse.kr to generate the // impulses directly. // We evaluate this function multiple times using .dup so that // we get a whole set of impulses with random phase positions. { Impulse.kr(rate, 1.0.rand, 1.0.bilinrand) }.dup(10).sum }; ~regularroll.plot(2); ) Fig 31.7: ground bumping ( // This signal contribution to rolling signature based on Mathias Rath's idea - see 'The Sounding Object' // (ajf2009) // ~irregularground = { |rate=10| var trigs = Dust.kr(rate); EnvGen.ar( Env([0,0,-1,1.5,-1,1,0], [0.1, 0.1, 0.001, 0.001, 0.1, 0.1], 'sine'), trigs ) * 0.1 }; ~irregularground.plot(4) ) Fig 31.8: putting it all together (You must have run figs 31.6 and 31.7 to get their functions defined.) The sound of a can rolling a little and coming to a stop. ( x = { var rate, strike, son; // rate of motion starts fast and tails off rate = XLine.kr(4, 0.001, 8, doneAction: 2); // This rate affects both the regular rolling, and the irregular ground contacts. strike = ~irregularground.(rate*2) * 0.04 + K2A.ar(~regularroll.(rate) * 0.1) ; // Force the strikes to die off in intensity: strike = strike * XLine.ar(1, 0.0001, 8); // And here are the tin-can resonances as in fig 31.3: son = Ringz.ar(strike, [359, 426, 1748, 3150], 0.2).sum; son = HPF.ar(son.clip2(0.6), 300); son * 0.2 }.play; ) Dan Stowell