def ldn(lday, lnight, hours=(15.0, 9.0), adjustment=(0.0, 10.0)):
    """
    Calculate :math:`L_{dn}` from :math:`L_{day}` and :math:`L_{night}`.

    :param lday: Equivalent level during day period :math:`L_{day}`.
    :param lnight: Equivalent level during night period :math:`L_{night}`.
    :param hours: Hours per period.
    :param adjustment: Correction factor per period.
    :returns: :math:`L_{dn}`

    .. seealso:: :func:`acoustics.standards.iso_1996_1_2003.composite_rating_level`
    """
    lday = np.asarray(lday)
    lnight = np.asarray(lnight)
    return composite_rating_level(np.vstack((lday, lnight)).T, hours, adjustment)
def ldn(lday, lnight, hours=(15.0, 9.0), adjustment=(0.0, 10.0)):
    """
    Calculate :math:`L_{dn}` from :math:`L_{day}` and :math:`L_{night}`.

    :param lday: Equivalent level during day period :math:`L_{day}`.
    :param lnight: Equivalent level during night period :math:`L_{night}`.
    :param hours: Hours per period.
    :param adjustment: Correction factor per period.
    :returns: :math:`L_{dn}`

    .. seealso:: :func:`acoustics.standards.iso_1996_1_2003.composite_rating_level`
    """
    lday = np.asarray(lday)
    lnight = np.asarray(lnight)
    return composite_rating_level(
        np.vstack((lday, lnight)).T, hours, adjustment)