bisbigliando

1. (music) A special tremolo effect on the harp where a chord or note is rapidly repeated at a low volume. Usually, the effect is achieved by both hands playing adjacent strings set to the same pitches and can sound like strumming a guitar or “watery“. On sheet music, it is represented by three thick lines connecting the notes to be trilled.

Actually, that is more like a tremolo or enharmonic trill. Bisbigliando generally means a triad played with both hands on either the same notes or different inversions that overlap. A famous example of it is in Chabrier’s Espana. There are also bisbigliando passages that travel up and down the harp, a famous example of which is in the Pierne Impromptu-Caprice which starts at the top and works its way down to set at the bottom. Hasselman’s Follets is all bisbigliando. The special quality of a bisbigliando comes from replacing over and over on the same strings, barely touching them.

Playing two adjacent notes is a trill, and a third apart or more is a tremolo. Playing a chord as an arpeggio over and over is also a tremolo.