/** Wrapper for start */
  public void start() {
    if (parent != null) {
      parent.runOnUiThread(
          new Runnable() {

            @Override
            public void run() {
              if (wa != null) {
                wa.detectActivation();
              }
            }
          });
    }
  }
  /** Wrapper for stoping listening */
  public void stopListening() {

    if (parent != null) {
      parent.runOnUiThread(
          new Runnable() {

            @Override
            public void run() {
              if (wa != null) {
                wa.stopListening();
              }
            }
          });
    }
  }