- Barry Kernfeld
The basic pulse underlying measured music and thus the unit by which musical time is reckoned; the beat, though not always sounded, is always perceived as underpinning the temporal progress of the music, and it is only the presence of the beat that allows rhythm to be established. This article describes the ways in which the beat is expressed in jazz, and the relationship between the underlying pulse and the rhythms played by jazz musicians.
Meter is the grouping of beats in a regularly recurring pattern (the bar or measure) defined by accentuation (see §4 below). At a higher level than the beat and in more complex ways, meter (whether explicitly marked or only sensed) provides the temporal framework of the music within which rhythm is established and perceived. Meter is expressed in terms of the number of beats of a certain value that occur in the bar. In notated music it is indicated by a pair of numerals, one placed above the other, known as the time signature: the upper numeral indicates the number of beats in the bar, the lower the value accorded to each beat. Thus the time signature shown in ...