amp(vol, t) {
    if (t) {
      var rampTime = t || 0;
      var currentVol = this.output.gain.value;
      this.output.gain.cancelScheduledValues(p5sound.audiocontext.currentTime);
      this.output.gain.setValueAtTime(
        currentVol,
        p5sound.audiocontext.currentTime
      );
      this.output.gain.linearRampToValueAtTime(
        vol,
        rampTime + p5sound.audiocontext.currentTime
      );
    } else {
      this.output.gain.cancelScheduledValues(p5sound.audiocontext.currentTime);
      this.output.gain.setValueAtTime(vol, p5sound.audiocontext.currentTime);
    }
  }
Set amplitude (volume) of a mic input between 0 and 1.0. <br/>

 @method  amp
 @for p5.AudioIn
 @param  {Number} vol between 0 and 1.0
 @param {Number} [time] ramp time (optional)