def denormalize_db_spectrogram(spec, high=20.0, low=-100.0):
    """
    Denormalizes normalized spectrum into db-spectrum.

    Args:
        spec: normalized spectrum
        high (float): maximum db level
        low (float): mean db level

    Returns:
        denormalized db spectrum
    """
    mid = (low + high) / 2.0
    scale = high - mid
    return spec * scale + mid
