This by his thought of self, the nufs. Undifferentiated Sound exists above the mind-mesh, and in the mental plane it exists as all different sounds. These need not clash but when they are attuned to particular ears, and then focused by particular thoughts - especially by that nufs, or thought of self - their real rhythm and vibration is effected and they are perceived as disharmonies. This disharmony is not real, it is not objective, it is subjective - the result of relating reality to the false self.