return neg inf if ref outside of thresh everywhere

        ss.append(ss_seg)

    # round to 2 decimals. this is just to be in line with the meg conformance tool

    if np.all(segment_counter == 0):

        # the reference signal was outside of [thresh_lowm thresh_high] for all segments -> return -inf

        # note that this is not in line with the mpeg conf tool which gives +/-0.0 in this case

        ssnr = np.asarray([-np.inf] * len(segment_counter))

    else:

        # round to 2 decimals. this is just to be in line with the mpeg conformance tool

        ssnr = np.round(10 * np.log10(10 ** (np.sum(ss, axis=0) / segment_counter) - 1), 2)

    return ssnr