5 ms·

OK, so why do we sometimes use 6/8 instead of 3/4? And rarely 2/2 instead of 4/4?

by nandemo 15y ago

elwin 15y ago
Mostly to indicate tempo and style. A 3/4 measure and a 6/8 measure are the same length, but the 6/8 has twice as many beats at twice the rate. So a composer would use a 6/8 signature for a faster-moving piece with a lot of eighth notes. Similarly, a slow piece would have a 2/2 signature instead of 4/4.
- nitrogen 15y ago
  I think you may have the 2/2 vs. 4/4 reversed. In a 2/2 piece, quarter notes will be played twice as fast as in a 4/4 piece at the same tempo. From Wikipedia (http://en.wikipedia.org/wiki/Time_signature#Most_frequent_time_signatures http://en.wikipedia.org/wiki/Time_signature#Most_frequent_ti...): alla breve, cut time: used for marches and fast orchestral music. Frequently occurs in musical theater. Sometimes called "in 2", but may be notated in 4.
- corin_ 15y ago
  That really isn't the case, that is the job of the tempo, a BPM speed set by the composer. The intended difference is purely that 3/4 groups quavers into groups of two, 6/8 into groups of three.
grifaton 15y ago
6/8 really has two beats in a bar, each beat containing three quavers, while 3/4 has three beats in a bar.
icarus_drowning 15y ago
Because the micro-pulse of 6/8 is different than 3/4. 3/4 is naturally emphasized as "1 2 3 1 2 3. In contrast, 6/8 is naturally emphasized with a micro pulse of 1 2 3 4 5 6, which produces a strong pulse on 1, a slightly weaker pulse on 4, and a macro pulse of "1 2. (Think 4/4 with triplets). You thus get a much different feeling from 6/8 than 3/4.
- nandemo 15y ago
  OK, my issue was with your statement that time signatures are simply fractions. If that were true than 6/8=3/4. But I understand you were presenting a simplified explanation.
eavc 15y ago
Primarily for reasons of legibility, in my opinion. Technically, any piece in duple meter could be written in any duple meter and any triple meter piece could be written in triple meter. In fact, you could even write a triple meter piece in duple meter if you are willing to notate everything as a triplet. Also, as some of the answers below show, part of legibility is in supporting the speed or the feel of the piece. (Also 2/2 is a fairly common time signature better known as cut-time. Many marches, for example, use this.)

OK, so why do we sometimes use 6/8 instead of 3/4? And rarely 2/2 instead of 4/4?

by nandemo 15y ago

OK, so why do we sometimes use 6/8 instead of 3/4? And rarely 2/2 instead of 4/4?

elwin 15y ago

Mostly to indicate tempo and style. A 3/4 measure and a 6/8 measure are the same length, but the 6/8 has twice as many beats at twice the rate. So a composer would use a 6/8 signature for a faster-moving piece with a lot of eighth notes. Similarly, a slow piece would have a 2/2 signature instead of 4/4.

nitrogen 15y ago
I think you may have the 2/2 vs. 4/4 reversed. In a 2/2 piece, quarter notes will be played twice as fast as in a 4/4 piece at the same tempo. From Wikipedia (http://en.wikipedia.org/wiki/Time_signature#Most_frequent_time_signatures http://en.wikipedia.org/wiki/Time_signature#Most_frequent_ti...): alla breve, cut time: used for marches and fast orchestral music. Frequently occurs in musical theater. Sometimes called "in 2", but may be notated in 4.
corin_ 15y ago
That really isn't the case, that is the job of the tempo, a BPM speed set by the composer. The intended difference is purely that 3/4 groups quavers into groups of two, 6/8 into groups of three.

grifaton 15y ago

6/8 really has two beats in a bar, each beat containing three quavers, while 3/4 has three beats in a bar.

icarus_drowning 15y ago

Because the micro-pulse of 6/8 is different than 3/4. 3/4 is naturally emphasized as "1 2 3 1 2 3. In contrast, 6/8 is naturally emphasized with a micro pulse of 1 2 3 4 5 6, which produces a strong pulse on 1, a slightly weaker pulse on 4, and a macro pulse of "1 2. (Think 4/4 with triplets). You thus get a much different feeling from 6/8 than 3/4.

nandemo 15y ago
OK, my issue was with your statement that time signatures are simply fractions. If that were true than 6/8=3/4. But I understand you were presenting a simplified explanation.

eavc 15y ago

Primarily for reasons of legibility, in my opinion. Technically, any piece in duple meter could be written in any duple meter and any triple meter piece could be written in triple meter. In fact, you could even write a triple meter piece in duple meter if you are willing to notate everything as a triplet. Also, as some of the answers below show, part of legibility is in supporting the speed or the feel of the piece. (Also 2/2 is a fairly common time signature better known as cut-time. Many marches, for example, use this.)