add small constant to ref_power to avoid zero in log

        ss_seg = np.log10(1 + nrg_ref / (denom_add + nrg_diff))

        # only sum up segments that fall inside the thresholds

        ref_power = 10 * np.log10(nrg_ref / len_seg)

        # add smapp eps to nrg_ref to prevent RuntimeWarnings from numpy

        ref_power = 10 * np.log10((nrg_ref + 10**-7) / len_seg)

        zero_mask = np.logical_or(ref_power < thresh_low, ref_power > thresh_high)

        ss_seg[zero_mask] = 0