def METHOD_NAME(root_path):
    """Setup the hearing aid and make some dummy data file for testing
    Args:
        root_path (pathlib.Path): Path to temporary directory
    Returns:
        tuple: (gha_hearing_aid, stereo_signal, tmp_filenames)
            gha_hearing_aid (GHAHearingAid): Hearing aid object
            stereo_signal (np.ndarray): Dummy stereo signal stored in the files
            tmp_filenames (list): List of temporary filenames
    """
    gha_hearing_aid = GHAHearingAid()
    tmp_filenames = [str(root_path / f"xxx.CH{chan}.wav") for chan in [1, 2, 3, 0]]
    stereo_signal = np.array(
        [[-0.1, 0.1, -0.1, 0.1, 0.0, -1.0], [-0.2, 0.2, -0.2, 0.2, 0.0, 1.1]]
    ).T  # <- signals are store with channels as columns
    for filename in tmp_filenames:
        write_signal(
            filename,
            stereo_signal,  # <- signals are stored with channels as columns
            gha_hearing_aid.sample_rate,
            floating_point=True,
        )
    return gha_hearing_aid, stereo_signal, tmp_filenames