def midi_to_hz(midi):
    """Convert MIDI numbers to Hz

    Parameters
    ----------
    midi : number or ndarray
        MIDI notes

    Returns
    -------
    freqs : number or ndarray
        Frequency/frequencies in Hz corresponding to `midi`
    """
    return 440.0 * 2.0 ** ((midi - 69.0) / 12.0)
