Strutt|Environmental Noise|Tonality|ISO 1996-2:2017 Tonality tests for the presence of tones by comparing the time-averaged sound pressure level (SPL) in a given 1/3 octave band with the time-averaged SPLs in the adjacent two 1/3 octave bands.
For a tone to be identified as present, the time-average SPL in the band of interest must exceed the time-averaged SPLs of both adjacent 1/3 octave bands by some constant level difference.
The assessment is carried out in accordance with Annex K of ISO-1996-2:2017. This Annex is provided for informative purposes only - it is a suggested methodology for identifying tones.
The aforementioned constant level differences given in Annex K are described as "possible choices"; nevertheless, these are the values that we have chosen to implement in Strutt. They are: