tempo

In music, the speed at which a piece should be played. One way of indicating the tempo of a piece of music is to give a metronome marking, which states the number of beats per minute; for example, ‘crotchet = 60’ means that there should be 60 crotchet beats to the minute, that is, one per second. Modern electronic metronomes measure tempo very accurately. Performers sometimes change or even ignore metronome markings, playing at a tempo that suits their interpretation of the music. However, the knowledge of performance practice gained by academic investigation into early music has encouraged performers to pay more attention to original tempo markings.

Music written before the development of precise metronomes could only give a vague idea of speed, and was often notated in a confusing manner. The system of time signatures that was developed during the Renaissance used symbols which, as well as giving the number of beats per bar, gave some indications of speed. In the 17th century, tempo was indicated by Italian words such as ‘allegro’ (lively), ‘presto’ (quick), or ‘lento’ (slow). These words only gave a vague idea of speed to modern musicians, but as the performers of the time dealt only with their contemporary music, norms of tempo were taken as read among most players and composers, although those extending the musical language, such as Ludwig van Beethoven, did have problems as his use of precise markings show. Additionally, descriptive tempo markings have the advantage of indicating mood: for example, ‘allegro’ not only conveys the idea of quickness, but also brightness; and ‘largo’ means broad and expansive, but also implies slowness. The expressive qualities of these verbal tempo indications mean that we still use them today, often alongside precise metronome markings.

When Johann Maëlzel developed the metronome in the 19th century, a precise way of describing tempo became possible. The beat of the music could be expressed as the number of beats per minute. For example, ‘crotchet = 120’, meant 120 crotchet beats to be played per minute. By using electronic metronomes, it is now possible to perform music to a very high degree of accuracy, and this has had a profound effect on performance practice in the late 20th century. Other factors influence the choice of tempo at any one time, and a truly musical interpretation often relies on changes in the underlying tempo throughout a piece, such as ‘accelerando’ (getting faster), ‘ritardando’ (getting slower), or ‘rubato’ (with a beat that is not strictly regular).