 Lennon, McCartney and Harrison's three-part harmony singing was another musical detail that came to typify the "Rubber Soul" sound.According to musicologist Walter Everett, some of the vocal arrangements feature the same "pantonal planing of three-part root-position triads" adopted by the Byrds, who had initially based their harmonies on the style used by the Beatles and other British Invasion bands.Riley says that the Beatles softened their music on "Rubber Soul", yet by reverting to slower tempos they "draw attention to how much rhythm can do".