Normalised Noise Energy (NNE) is an acoustic measure of the voice assesses the relative level of vocal noise to  that  of harmonics,  but bases the analysis on a relatively small number of vocal periods (as opposed to individual cycles as in the HNR) and  is therefore much  faster to  calculate. This has an added  advantage that  it  avoids the  effects of  drift  in fundamental frequency or intensity during the utterance which can be a problem in the calculation of the noise component of the HNR.