Specific time – compound time signatures
The bottom number represents the note value of the subdivisions of the basic pulse of the music (in this case the 8 represents the quaver or eighth-note). The top number indicates how many of these subdivisions appear in each measure. Usually each beat is composed of three subdivisions. To derive the unit of the basic pulse in compound meters, double this value and add a dot, and divide the top number by 3 to determine how many of these pulses there are each measure. This example announces that each measure is the equivalent length of two dotted crotchets (dotted quarter-notes). You would pronounce this as "Six Eight Time.