Bisbigliando ("whispering" in 
Italian) is 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 adjecent strings set to the same 
pitches.  This is possible because of enharmonic spellings created by the pedals.
It can sound like strumming a 
guitar or even "watery".
On sheet music, it is represented by three thick lines connecting the notes to be trilled.
 
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