Spectral Amplitude Normalization  (default setting: "No")

NO

For the vast majority of cases, this parameter should be set to "No". Selecting "No" will estimate the amplitudes of the submitted signal's spectral components based on the amplitude envelope of the signal portion analyzed, assuming that the maximum possible signal amplitude is 1.
Complex signals with maximum amplitude ≤ 1 have spectral components whose amplitudes is necessarily < 1.

Select "No" if preserving the intensity relations among the files/file-portions you will be analyzing is significant to your research question.
Selecting "No" will be appropriate to most analysis contexts, whether the application will be calculating a single roughness value at a user-defined point in time or a series of roughness values (i.e. roughness profile) at user-defined, regular time intervals. Selecting "No" is strongly recommended when calculating roughness values for signals that have been used as stimuli in a perceptual experiment.

YES

Selecting "Yes" will scale up the amplitudes of the signal's spectral components so that the amplitude of the strongest component will be equal to 1.

Select "Yes" if preserving the intensity relations among the files/file-portions you will be analyzing is not significant to your research question.
For example: Selecting "Yes" would be appropriate for theoretical roughness comparisons among isolated vertical sonorities (harmonic intervals, chords, etc.), different isolated orchestrations of the same vertical sonorities, etc.. Selecting "Yes" essentially performs an intensity (not loudness) equalization over time on the submitted signal's spectrum and is most useful when addressing theoretical questions that can benefit from such equalization.
For example, calculating two roughness profiles for the same signal, with Normalization set to "No" and "Yes" respectively, will permit examination of the contribution of spectral intensity variations to the roughness profile of the submitted signal.

Note: Spectral amplitude normalization, discussed here, is not equivalent to signal normalization. Regardless of the setting for the spectral normalization parameter, it is advised to adjust signal levels so that their maximum level falls within the range -3 to -10dB before submitting them for roughness profile calculation. This will ensure that the dynamic range of the analysis will be utilized most efficiently.