This classical comedy theatre balances the more serious themes of nō. While nō is mainly music-based in nature, kyōgenis largely dialogue-based, though a number of songs and dances exist which tend to mimic the chant and dance style of nō. The two are traditionally performed alternately in the same programme, and they share a common heritage; in general, kyōgen is also inferred when speaking about the world of nō. In addition to their own kyōgen repertory of comic plays, kyōgen actors always appear in the interlude (ai) roles in nō plays, which are usually not comic in nature. Similarly, nō instrumentalists also sometimes appear in kyōgen plays, though their participation is not nearly as complex as it is for nō. The vocal and movement training methods of the two forms are very similar.