What creates the beating tones that are such a distinctive feature of balinese gamelan?

Gamelan gong kebyar is a type of balinese gamelan known particularly for its shimmering sound and interlocking parts. The pair of instruments are detuned to create the characteristics shimmering effect known as beating tones. Some musical features also include: dynamic extreme contrast, fast interlocking rhythms, multi layered elements create a polyphonic texture, sudden starts and stops, impressive precision in performance, little or in improvisation and colotomic structure based on intervals of time which instruments used to mark intervals of time.