getLevel(channel) {
    if (typeof channel !== 'undefined') {
      if (this.normalize) {
        return this.stereoVolNorm[channel];
      } else {
        return this.stereoVol[channel];
      }
    } else if (this.normalize) {
      return this.volNorm;
    } else {
      return this.volume;
    }
  }
Returns a single Amplitude reading at the moment it is called.
 For continuous readings, run in the draw loop.

 @method getLevel
 @for p5.Amplitude
 @param {Number} [channel] Optionally return only channel 0 (left) or 1 (right)
 @return {Number}       Amplitude as a number between 0.0 and 1.0
 @example
 <div><code>
 function preload(){
   sound = loadSound('assets/beat.mp3');
 }

 function setup() {
   let cnv = createCanvas(100, 100);
   cnv.mouseClicked(toggleSound);
   amplitude = new p5.Amplitude();
 }

 function draw() {
   background(220, 150);
   textAlign(CENTER);
   text('tap to play', width/2, 20);

   let level = amplitude.getLevel();
   let size = map(level, 0, 1, 0, 200);
   ellipse(width/2, height/2, size, size);
 }

 function toggleSound(){
   if (sound.isPlaying()) {
     sound.stop();
   } else {
     sound.play();
   }
 }
 </code></div>