forwardX(xVal, time) {
    var t = time || 0;
    if (typeof xVal === 'number') {
      this.listener.forwardX.value = xVal;
      this.listener.forwardX.cancelScheduledValues(
        this.ac.currentTime + 0.01 + t
      );
      this.listener.forwardX.linearRampToValueAtTime(
        xVal,
        this.ac.currentTime + 0.02 + t
      );
    } else if (xVal) {
      xVal.connect(this.listener.forwardX);
    }
    return this.listener.forwardX.value;
  }
//   * Getter and setter methods for orient coordinates
  //   * @return {Number}      [updated coordinate value]
  //