def t60_fitzroy(surfaces, alpha, volume, c=SOUNDSPEED):
    Sx = np.sum(surfaces[0:2])
    Sy = np.sum(surfaces[2:4])
    Sz = np.sum(surfaces[4:6])
    St = np.sum(surfaces)
    alpha = _is_1d(alpha)
    a_x = np.average(alpha[:, 0:2], weights=surfaces[0:2], axis=1)
    a_y = np.average(alpha[:, 2:4], weights=surfaces[2:4], axis=1)
    a_z = np.average(alpha[:, 4:6], weights=surfaces[4:6], axis=1)
    factor = -(Sx / np.log(1.0-a_x) + Sy / np.log(1.0-a_y) + Sz / np.log(1-a_z))
    t60 = 4.0 * np.log(10.0**6.0) * volume * factor / (c * St**2.0)
    return t60
Reverberation time according to Fitzroy.
dataset/ETHPy150Open python-acoustics/python-acoustics/acoustics/room.py/t60_fitzroy