Adding harmonics to a voice input

One easy way to add harmonics is to use the [PitchShift] UGen. See its helpfile for more details.

An alternative approach is to use the [Pitch] UGen to track the pitch contour, and use that in synthesis. This allows you to generate sounds matching the pitch of the input but with any kind of texture.

// (Dan Stowell) (public domain 2006)

// USE HEADPHONES to prevent feedback.

(

x = {

var son, freq, hasFreq, amp, out, harm;

son = AudioIn.ar(1); // get first channel of sound input

# freq, hasFreq = Pitch.kr(son); // Pitch of input signal

amp = Amplitude.ar(son); // Amplitude of input signal

harm = SinOsc.ar(freq * 2, 0, amp * hasFreq);

Pan2.ar(harm + son)

}.play;

)

x.free; // Use this to stop the synth

The above example adds only one harmonic. You can extend this to create multiple harmonics quite easily, for example by using an array of pitch ratios rather than a single ratio (and therefore creating an array of sine oscillators); or you could change the texture by using a more unusual oscillator (e.g. [Saw] or [Gendy1] or [HenonN]).

If you want a large number of controllable overtones then a bank of separate sine oscillators will become quite computationally intensive, so a good alternative is to use the general wavetable oscillator [Osc] instead of SinOsc. The wavetable (a buffer) can be filled with a wave representing the harmonic profile you're interested in, and only one oscillator is needed to read it back.

Let's implement this, and add a GUI for controlling the contents of the wavetable:

// (Dan Stowell, kernel) (gpl 2006)

//first make and send the Synthdef so it's on the server

(

SynthDef(\oscPlayer, {|bufnum,balance=0.5,smooth=0.1|

var input,freq,hasFreq,amp,mix,wet;

input = AudioIn.ar(1); // get first channel of sound input

#freq,hasFreq = Pitch.kr(input); // pitch of input signal

amp = Amplitude.ar(input); // amplitude of input signal

wet = Osc.ar(bufnum,Lag.kr(freq,smooth), 0, amp);

mix = (input * (1-balance)) + (wet * balance);

Out.ar(0, Pan2.ar(mix));

}).add;

)

// select a GUI server:

GUI.cocoa; // use Mac OS X native GUI

GUI.swing; // use Java GUI

// Now to instantiate the synth and build the GUI.

// USE HEADPHONES to prevent feedback.

(

var win,buf,m,harmonics,maxHarmonics=60,theSynth;

win = Window("input harmonica",Rect(200,200,420,160)).front;

harmonics = Array.fill(maxHarmonics,0);

harmonics.put(0,1); // init array so first partial is alive

buf = Buffer.alloc(s, 4096, 1); // create buffer

buf.sine1(harmonics); // fill buffer

theSynth = Synth(\oscPlayer, [\bufnum, buf.bufnum], s);

m = MultiSliderView(win, Rect(5, 5, 350, 100))

.value_(harmonics)

.isFilled_(true)

.valueThumbSize_(3.0)

.indexThumbSize_(3.0)

.gap_(2)

.elasticMode_(1)

.action_({|v| buf.sine1(v.value)}); // fill buffer again

Button(win,Rect(5,110,70,20))

.states_([["CLEAR",Color.green,Color.black]])

.action_({var temp;

temp = Array.fill(maxHarmonics,0);

buf.sine1(temp);

m.value_(temp);

});

Button(win,Rect(80,110,65,20))

.states_([["RAND",Color.green,Color.black]])

.action_({|v| var temp;

temp = m.value.scramble;

buf.sine1(temp);

m.value_(temp);

});

Button(win,Rect(150,110,20,20))

.states_([["<<",Color.green,Color.black]])

.action_({|v| var temp;

temp = m.value.rotate(-1);

buf.sine1(temp);

m.value_(temp);

});

Button(win,Rect(175,110,20,20))

.states_([[">>",Color.green,Color.black]])

.action_({|v| var temp;

temp = m.value.rotate(1);

buf.sine1(temp);

m.value_(temp);

});

Slider(win, Rect(365,5,20,100))

.value_(0.1)

.action_({|v| theSynth.set(\smooth,[0,1,\lin,0.001].asSpec.unmap(v.value))});

Slider(win, Rect(390,5,20,100))

.value_(0.5)

.action_({|v| theSynth.set(\balance,v.value)});

)