constructor(output, number) {

    super();

    /**
     * @type {Output}
     * @private
     */
    this._output = output;

    /**
     * @type {number}
     * @private
     */
    this._number = number;

    /**
     * @type {number}
     * @private
     */
    this._octaveOffset = 0;

  }
Creates an `OutputChannel` object.

@param {Output} output The [`Output`](Output) this channel belongs to.
@param {number} number The MIDI channel number (`1` - `16`).