noteADSR(note, a, d, s, r, timeFromNow = 0) {
    var now = p5sound.audiocontext.currentTime;
    var t = now + timeFromNow;
    this.audiovoices[this.notes[note].getValueAtTime(t)].setADSR(a, d, s, r);
  }
noteADSR sets the envelope for a specific note that has just been triggered.
 Using this method modifies the envelope of whichever audiovoice is being used
 to play the desired note. The envelope should be reset before noteRelease is called
 in order to prevent the modified envelope from being used on other notes.

 @method  noteADSR
 @for p5.PolySynth
 @param {Number} [note]        Midi note on which ADSR should be set.
 @param {Number} [attackTime]  Time (in seconds before envelope
                               reaches Attack Level
 @param {Number} [decayTime]   Time (in seconds) before envelope
                               reaches Decay/Sustain Level
 @param {Number} [susRatio]    Ratio between attackLevel and releaseLevel, on a scale from 0 to 1,
                               where 1.0 = attackLevel, 0.0 = releaseLevel.
                               The susRatio determines the decayLevel and the level at which the
                               sustain portion of the envelope will sustain.
                               For example, if attackLevel is 0.4, releaseLevel is 0,
                               and susAmt is 0.5, the decayLevel would be 0.2. If attackLevel is
                               increased to 1.0 (using <code>setRange</code>),
                               then decayLevel would increase proportionally, to become 0.5.
 @param {Number} [releaseTime]   Time in seconds from now (defaults to 0)