The melodies are set to madenda, the Sundanese variant of the pelog mode, or slendro, or a free combination of the two, or an alternating combination. The melodies are usually in the pelog or madenda scales, while the fixed pitch idiophonic accompaniment is strictly in slendro. This combination contrasts with the gamelan tradition. The scales of these modes, intonation and tonic are difficult and not consistent. Intonation may be further obscured by the characteristic vibrato. These melodies in jaipongan can also be stereotypical; so much of the expressiveness and uniqueness comes in the introduction, improvised or pre-composed. It often establishes the modal pattern.