Frequency Analysis Resolution  (default setting: "10Hz")

   

The frequency resolution (bandwidth) of the analysis can be set to either 10Hz or 20Hz, with the shortest files that can be analyzed being ~320ms- and ~160ms-long respectively. It is important to note that this length limit does not apply to the time interval for roughness and spectral profile estimation, which can be as short as 1ms, although such short time intervals may be both impractical (in terms of the amount of data reported) and meaningless (in terms or roughness changes). Rather, the limit applies to the shortest file that can be submitted for analysis and to the earliest and latest points within a file for which roughness values and spectra can be calculated.
 
For example, given frequency resolution of 10Hz, the earliest (latest) point within a file for which a roughness value can be calculated will be ~160ms from the beginning (end) of the file, corresponding to the mid-point of the shortest file that can be analyzed.
More importantly, although 10Hz frequency resolution means that frequency components less than 10Hz apart will remain unresolved, the frequency values reported will not necessarily be in multiples of 10 but will have <1Hz precision. For more details, make sure you read the information on the signal analysis method used. 

The default value for this parameter is "10Hz." The value "20Hz" should be selected only if it is certain that the sound files submitted for analysis contain no components separated by less than 20Hz in frequency.
For example, 20Hz represent ~ a minor 2nd harmonic interval for fundamental frequencies around F4 (see a chart of equal temperament fundamental frequencies). With the analysis bandwidth set at 20Hz, minor 2nd harmonic intervals below F4 will correspond to fundamental frequencies that will be interpreted as unisons by the analysis, distorting the roughness calculation results. The lower the fundamental frequency of the tones making up the sound files analyzed, the more severe the distortion of the roughness calculation results will be. In fact, for fundamental frequencies around F2, 20Hz bandwidth represents ~ a major 3rd, and would wrongly interpret this and all narrower intervals as unisons. The only benefits of selecting 20Hz over 10Hz resolution are a) the ability to analyze shorter files and b) faster calculations.