import processing.sound.*;

AudioIn input;
Amplitude loudness;

void setup() {
  size(640, 360);
  background(255);

  input = new AudioIn(this, 0);

  input.start();
  loudness = new Amplitude(this);

  loudness.input(input);
}


void draw() {
  float volume = loudness.analyze() * 350;

  background(125, 255, 125);
  noStroke();
  fill(255, 0, 150);
  ellipse(width/2, height/2, volume, volume);
}