The accompaniment for a Peking opera performance usually consists of a small ensemble of traditional melodic and percussion instruments. The lead melodic instrument is the "jinghu", a small, high-pitched, two-string spike fiddle. The "jinghu" is the primary accompaniment for performers during songs. Accompaniment is heterophonic – the "jinghu" player follows the basic contours of the song's melody, but diverges in pitch and other elements. The "jinghu" often plays more notes per measure than the performer sings, and does so an octave lower. During rehearsal, the "jinghu" player adopts his or her own signature version of the song's melody, but also must adapt to spontaneous improvisations on the part of the performer due to changed performance conditions. Thus, the "jinghu" player must have an instinctive ability to change his or her performance without warning to properly accompany the performer.