def pitch2hz(p, beta=12, ref_frq=440.0):
    """Convert pitch to frequency.

    Parameters
    ----------
    p : np.ndarray, float
        midi pitch
    beta : int
        equal divisions of the octave
    ref_frq : float, optional
        Description

    Returns
    -------
    frq : np.ndarray, float
        frequency
    """
    return 2 ** ((p - 69) / beta) * ref_frq
