 While harmonicity and inharmonicity can also be considered NLDs, harshness differs from them, as well as from roughness, once it reckons for a distinguished perceptual audio feature expressed by the summary spectral periodicity.This feature is especially clear in single-pitch, single-note, musical audio, where the timbre of two different musical instruments can greatly differ in levels of harshness (e.g., the difference in harshness between a flute and a saxophone is evident).As it is supposed to be, harshness is independent of all others NLDs.