function setup() {
  createCanvas(710, 256);
  fill(255, 40, 255);

  filter = new p5.BandPass();

  noise = new p5.Noise();

  noise.disconnect(); // Disconnect soundfile from main output...
  filter.process(noise); // ...and connect to filter so we'll only hear BandPass.
  noise.start();

  fft = new p5.FFT();

  // update description text
  p = createP(description);
  var p2 = createP('Draw the array returned by FFT.analyze( ). This represents the frequency spectrum, from lowest to highest frequencies.');
}
Example: Apply a p5.BandPass filter to white noise.
 Visualize the sound with FFT.
 Map mouseX to the bandpass frequency
 and mouseY to resonance/width of the a BandPass filter