MuseScore -- Index -- Tremolo
Tremolo is the rapid repetition of one note or a rapid alternation
between two or more notes. It is indicated by strokes through the stems
of the notes. If the tremolo is between two or more notes, the bars
are drawn between them.
There are separate symbols for one note and two note tremoli in the
tremolo palette.
In a two note tremolo every note has the value of the whole tremolo
duration. To enter a tremolo with the duration of a half note (minum)
first enter two normal quarter notes (quavers). After dragging a
tremolo symbol to the first note the note values automatically double
to half notes.