The trill is a musical ornament consisting of a rapid alternation between two adjacent notes of a scale (compare tremolo).

In modern musical notation a trill is generally indicated with the letters tr above the trilled note. This has sometimes been followed by a squiggly line, and sometimes in the past, the squiggly line on its own was used. The following two notations are equivalent:

Both the "tr" and the squiggly line are necessary for clarity when the trill is expected to be applied to more than one note (or to tied notes). Also, when attached to a single notehead in one part that corresponds to smaller note values in another part, it leaves no room for doubt if both the letters and the line are used.

The usual way of executing a trill is to rapidly alternate between the note indicated and the note directly above it in the given scale (unless the trill indicates an accidental).

Listen to an example of a short passage ending on a trill. The first time, the passage ends in a trill, and the second, the passage does not.

The trill is a musical ornament consisting of a rapid alternation between two adjacent notes of a scale (compare tremolo).

In modern musical notation a trill is generally indicated with the letters tr above the trilled note. This has sometimes been followed by a squiggly line, and sometimes in the past, the squiggly line on its own was used. The following two notations are equivalent:

Both the "tr" and the squiggly line are necessary for clarity when the trill is expected to be applied to more than one note (or to tied notes). Also, when attached to a single notehead in one part that corresponds to smaller note values in another part, it leaves no room for doubt if both the letters and the line are used.

The usual way of executing a trill is to rapidly alternate between the note indicated and the note directly above it in the given scale (unless the trill indicates an accidental).

Listen to an example of a short passage ending on a trill. The first time, the passage ends in a trill, and the second, the passage does not. (Vorbis)

It should be noted that this is an approximation of how a trill might be executed. In many cases, the rate of the trill will not remain constant as indicated here, but will start slower and become more rapid. Whether a trill is played in this way or not is largely a matter of taste.

The number of alternations between notes can vary according to the length of the note in question. At slower tempos a note will last longer, meaning more notes can be played in the trill, but with a fast tempo and short note a trill might be reduced to nothing more than the indicated note, the note above and the indicated note again.

Trills may also be played beginning on the note above the one indicated (the auxiliary note). Additionally, a trill is often ended by playing the note below the one indicated followed by the note itself.

Trills are often indicated in tuned percussion as well, especially timpani, in which case they are calling for a tremolo or roll.

Baroque

In the Baroque period, a number of signs indicating specific patterns with which a trill should be begun or ended were used. In the Klavierbüchlein für Wilhelm Friedemann Bach, Johann Sebastian Bach lists a number of these signs together with the correct way to interpret them.

Unless one of these specific signs is indicated (and beyond the Baroque period they are very rare), there are no definite rules about whether a trill starts on the main note or the auxiliary note and whether the above alternative ending or some similar alternative beginning is used. However, in general, classical music before and during the time of Mozart is executed beginning on the auxiliary note, and music from after the time of Mozart starts on the main note. These factors, together with the overall rate of the trill and whether that rate is constant or variable, can only be determined by considering the context in which the trill appears, and is usually to a large degree a matter of opinion with no single "right" way of executing the ornament.

Generally, the note to be trilled to is determined by the key signature. For example, in C major, a trill on E would be a trill between E and F. If the composer or arranger wanted a trill to F-sharp, he would have to add a small accidental (a sharp in this case) above the "tr."

The trill is frequently found in classical music for all instruments, although it is more easily executed on some than others. It is relatively easy to produce a trill on the piano, but on the trombone it is produced by quickly alternating partials. On the clarinet, trills across the break are found only in virtuoso literature. (Courtesy of Wikipedia)