Accents: Contrast is created by means of highlighting certain elements of the music, either regularly or irregularly. When timbre or duration are not at play, accents are the only rhythmic criteria. Timbre: Contrast is produced by hearing/playing different tone colors in turn, either regularly or irregularly. When accents or duration are not at play, timbre is the only rhythmic criterion. Duration: Contrast is produced by the succession of unequal time val- ues. When accents or timbre are not at play, durations are the only rhythmic criteria. 16 As for meter, Arom adds that “it is in fact the most elementary manifestation of rhythm,” 17 made of identical durations with regular stress patterns. Fred Lerdahl and Ray Jackendoff suggest other definitions of the accent, of which they see three types: