Once you accept the idea of a pulse or beat, it becomes apparent that the beat can be relatively fast or slow. This speed is called the tempo. Our psychological sense of tempo is strongly related to the heartbeat. It has been scientifically proven that beats faster than the average speed of the human heart (about 80 beats per minute) tend to stimulate and excite, whereas those slower than the heartbeat have a calming effect.
The tempo of music is determined by the duration of the beat—how long it lasts. This determines the number of beats that occur per minute. This value is used to precisely define the tempo of the music.
Table 4.1 lists some average beat lengths associated with different types of music.