Double trill
Simultaneous execution of a trill on two different notes.
What it means
A double trill is the simultaneous execution of two trills on different notes, usually a third or a sixth apart. Both trills run in sync and at the same speed, producing a two-part, continuously shimmering band of sound rather than a single ornamented note.
In the notation
A double trill is notated as two trill signs (tr) stacked over the respective noteheads, to be played simultaneously, often joined by a shared wavy line that indicates the synchronous, matched execution of both.
Musical use
Double trills occur mainly on the piano, where both notes are played by the same hand or shared between both hands, and more rarely on string instruments as double stops. They create a particularly dense, rich effect and are used above all in virtuosic Romantic piano music as the climax of a build-up.
A double trill should be distinguished from a simple trill, which affects only one note, and from a chain trill, in which a single trill is carried forward across several successive notes rather than ornamenting two notes at once.
Performance practice
Practise both trill lines separately at an even tempo before combining them, so that both voices sound equally fast and equally loud. Pay particular attention that neither trill line outruns the other in speed, and slow down if necessary until both hands synchronise the double trill cleanly.