Bar
Counting the beats: the Bar
Synonyms
Bar, Measure, big One
Description
In music, the Beats are normally grouped in a larger (slower) time unit usually called Bar. The Bar or Measure will always group 1 or more Beats or Pulses. 4, 6 and 8 are the most common of this groupings. The indications or time signatures describe the basic Beat but also how many of this Beats are to be grouped in each Bar: 4/4, 6/8, 5/4, 7/8, 11/8, etc.
It is normal for the speed of the bar to be defined in reference to the speed of the beats it groups, however when we work with split Polyrhythms we can determine the speed of the bar in an absolute manner using BarsPM o Bars per minute. Each voice can then determine the speed of Beats per minute (BPM) pertaining their musical lines by dividing the BarsPM into the number of Beats that their Bar is grouping.
Example
A piece of music using split Polyrhythm in 7 and 5, shares the duration of the bar for both the voice in 7 and the voice in 5.
If the piece was to have a speed of bars of 30 BarsPM, the speed of the beats would be determined like this:
Voice in 5: 30 x 5 = 150 BPM Voice in 7: 30 x 7 = 210 BPM
