def mean_tl(tl, surfaces):
    try:
        tau_axis = tl.ndim - 1
    except __HOLE__:
        tau_axis = 0
    tau = 1.0 / (10.0**(tl/10.0))
    return 10.0 * np.log10(1.0 / np.average(tau, tau_axis, surfaces))
dataset/ETHPy150Open python-acoustics/python-acoustics/acoustics/utils.py/mean_tl