ModalNoise demo

Author: Kees van den Doel

This applet filters white noise through a bank of reson filters. You can set the frequencies, dampings, and gains of each reson with the sliders, or generate random settings with the button. The SourcePlayer does automatic gain control (AGC) so if you make a change that results in a large reduction in volume, for example going from lightly damped modes to highly damped modes, you may not hear anything. Pressing ResetAGC will reset the gain control in that case.

If you like more sliders, try this Applet.

Source code:

import jass.render.*;
import jass.engine.*;
import jass.generators.*;

/**
   Filter white noise through a modal resonbank.
   @author Kees van den Doel (kvdoel@cs.ubc.ca)
*/
public class ModalNoiseApplet extends AppletController {

    RandOut rout;
    SourcePlayer player;
    ModalObjectWithOneContact mob;
    ModalModel mm;
    
    int nmodes = 3;
    float srate = 44100.f;
    double fmin = 50;
    double fmax = srate/4;
    double dmin = 1;
    double dmax = srate/10;
    double amin = 0;
    double amax = 1;

    String[] names = new String[nmodes*3];
    double[] val =   new double[nmodes*3];
    double[] min =  new double[nmodes*3];
    double[] max = new double[nmodes*3];
    
    public void setNSliders() {
        nsliders = nmodes*3;
    }

    public void setNButtons() {
        nbuttons = 2;
    }
    
    public void initRandom() {
        for(int i=0;i< nmodes;i++) {
            mm.f[i] = (float)(fmin + (fmax-fmin)*Math.random());
            mm.d[i] = (float)(dmin + (dmax-dmin)*Math.random());
            mm.a[0][i] = (float)(amin + (amax-amin)*Math.random());
        }
    }
    
    public void start() {

        int bufferSize = 128*4;
        int bufferSizeJavaSound = 8*1024;
        rout = new RandOut(bufferSize);
        player = new SourcePlayer(bufferSize,bufferSizeJavaSound,srate);
        mm = new ModalModel(nmodes,1);
        mm.f = new float[nmodes];
        mm.d = new float[nmodes];
        mm.a = new float[1][nmodes];
        initRandom();
        mob =  new ModalObjectWithOneContact(mm,srate,bufferSize);
        try {
            player.addSource(mob);
            mob.addSource(rout);
        } catch(SinkIsFullException e) {
        }

        for(int i=0;i< nmodes;i++) {
            names[i] = "freq" + i + " ";
            names[i+nmodes] = "damping" + i + " ";
            names[i+2*nmodes] = "gain" + i + " ";
            val[i] = mm.f[i];
            val[i+nmodes] = mm.d[i];
            val[i+2*nmodes] = mm.a[0][i];
            min[i] = fmin;
            min[i+nmodes] = dmin;
            min[i+2*nmodes] = amin;
            max[i] = fmax;
            max[i+nmodes] = dmax;
            max[i+2*nmodes] = amax;
        }
        setValues(val,min,max,names);
        jButton[0].setText ("Randomize");
        jButton[1].setText ("Reset AGC");
        
        player.start();
    }

    protected void jButtonMousePressed (int k,java.awt.event.MouseEvent evt) {
        switch(k) {
        case 0:
            initRandom();
            for(int i=0;i< nmodes;i++) {
                val[i] = mm.f[i];
                val[i+nmodes] = mm.d[i];
                val[i+2*nmodes] = mm.a[0][i];
            }
            setValues(val,min,max,names);
            mob.computeFilter();
            player.resetAGC();
            break;
        case 1:
            player.resetAGC();
            break;
        }
    }
    
    protected void onSlider(int k) {
        if(k< nmodes) {
            mm.f[k] = (float)(super.val[k]);
        } else if(k< nmodes*2) {
            mm.d[k-nmodes] = (float)(super.val[k]);
        } else if(k< nmodes*3) {
            mm.a[0][k-2*nmodes] = (float)(super.val[k]);
        }
        mob.computeFilter();
    }
}