Why use odd time signatures?

I'm a beginner guitar player, and I'm trying to pick up some of the music theory behind the instrument, and one thing that I've sort of grasped is odd time signatures.

I know what they are, and I can read and play in them, but I still don't think I understand the purpose.

For example, let's say you have a riff or something, and it's in 5/4, so this riff is 5 quarter notes. Is there a difference between writing this riff in 5/4 or just writing the first 4 quarter notes of the riff in a measure of 4/4 and writing the final quarter note of the riff in the following measure, still in 4/4?

Is it just for organization/ease of reading's sake?

• As you learn to play guitar, I highly suggest you learn to count out the beat as you play. If you try to play a riff that is a 5/4 riff while counting “1 2 3 4 1 2 3 4”, I think you’ll understand for yourself why counting in five is better. Feb 12, 2019 at 23:49
• Try to dance a waltz on youtu.be/LHZpCVKaIGg?t=140, you might understand why 3/4 would be better.;) Feb 13, 2019 at 13:22
• @ToddWilcox has got it. This is tough to explain, but much easier to understand if you start counting along to music. Just try it, and you'll intuitively start understanding odd time signatures. Feb 13, 2019 at 15:26
• There's a rule in music that beats at the start of a bar, and at the half way point (if it's an even number) are emphasised, so the time signature gives us some of the 'feel'. Also, if your pattern isn't the same length as a number of bars, the start of the pattern will fall on different beats each time, making it harder to read and play. As with every way of breaking rules in music, this is sometimes done for effect (e.g. the drums are playing a 4/4 pattern while there's a 7/8 repeating melody. They slip out of phase with each other). Feb 14, 2019 at 10:39

It basically comes down to how the way the notes/beats are emphasised affects how your ear hears how the beats are grouped. Listening to a piece in 5/4, you'll hear that the beats are audibly in groups of 5. Try counting '1-2-3-4-5' with the beats in these songs, and you'll find that your counting stays in sync with the rhythmic pattern in the song...

Soundgarden's My Wave (Todd's excellent suggestion):

Dave Brubeck - Take Five:

Lalo Schifrin's theme to Mission Impossible:

XTC's English Roundabout (a personal favourite):

Notating pieces like these in 5/4 enables the first beats of the bar to line up with what's usually heard as the strong beat in the musical piece. This is the general pattern with time signatures - they're chosen to correspond somewhat with the actual audible 'feel' of the music. This helps the eye scan the score, as it can do so in the same size chunks that the ear is hearing.

• Perhaps an example more relevant to the asker’s interest would be the main riff to “My Wave” by Soundgarden (5/4), or “March Of Pigs” by Nine Inch Nails (7/8). Feb 12, 2019 at 23:47
• @ToddWilcox added 'My Wave' - great track! Feb 13, 2019 at 8:37
• Caution: "Take Five" is tricky, because everything hits the off-beats. The count is 1--2--3--4--5. Hmm, that boldface doesn't show up very well. Here's another, without numbers: o-O-O-o-O. Feb 13, 2019 at 13:17
• @PeteBecker very true - although the 1 often is the 'loud' beat, it isn't in all songs or styles, even though it may still be the main 'attractor point' for most of the phrasing. This points to a limitation in time signatures - they can't always pin down the specifics of the rhythmic feel of a piece. Feb 14, 2019 at 9:31
• Pink Floyd's Money is in 7/8 time I believe, it's another weird time signature. Feb 14, 2019 at 16:39

It is technically possible to notate in the way you describe, but it would probably not be a good idea. Time signatures are not only about cutting up the music into manageable chunks, but they also tend to guide things like stress and phrasing.

Most music isn't simply made up of a sequence of notes played robotically one after the other, but is rather made up of phrases; small musical "sentences" if you will. Ideally you want to write music down in a way which lines up nicely with how you intend the music to feel when performed.

If I; for example stuck - random bits of punctionation! into the middle of? a sentence (it would) become harder to understand what I'm: trying to convey. Just like punctuation should line up with the meaning of a sentence, so the time signature should line up with the "meaning" of a piece of music.

One place where this matters a lot is in regards to rhythm; as Michael Curtis mentions in his answer, time signatures generally determine which beats are felt as stressed or emphasized. In 4/4 the first beat is generally the "heaviest" followed by a secondary stress on beat three. In 3/4 there is a strong beat one followed by two relatively "weak" beats. 6/8 time is generally felt in terms of two beats, each divided into three etc. etc.

The "strong" or "heavy" beats receive more emphasis, and they are usually the points where we see chord changes and such (although this can of course be subverted for effect).

Thus, while you could notate almost any music in almost any time signature, you really want to notate it so that it best represents the kind of "feel" you're after in the music. Thus, if a piece is best felt in terms of five beats, then that's how it should be notated, even if it seems a bit awkward at first.

• "Inst eado fthi nkin gofi tasr ando mbit sofp uctu atio n,youc anth inko fita shav ingt hespa cesi nthe wron gpla ce." What I wrote there was "Instead of thiknng of it as random bits of punctuation, you can think of it as having the spaces in the wrong place," but with spaces very 4 characters instead of where they belonged. Needless to say, you see how much more readability can be had by putting the breaks in the right places in the music! Feb 13, 2019 at 6:19
• Notation can make a real difference. For example: I once wrote a choral piece with an irregular rhythm. But I wrote it out in 4/4, with off-beats (and some extra rests to realign). When performed, it didn't work well; the feeling was subtly wrong. When it was performed again, I printed it out again, but this time with no time signature, and barlines where they felt right. (IIRC, the first few bars had 3, 2, 3, 3, 2, 3, 4, 3, 4, 3, 3… beats.) And it sounded much better! People sang it with much more natural shaping and emphasis, even though the notes were the same. Feb 13, 2019 at 10:04
• @gidds: Time signatures can sometimes be important for reasons beyond saying where bar-lines go. Consider the sound of a rhytmic pattern like "dotted-quarter eighth quarter" in 3/4 or 6/8. The former is "Dum, daDum" and the latter is "Dum, Dadum". Without a time signature, a performer would have to guess where the stress belongs. Feb 13, 2019 at 17:23

When 5/4 is used to notate music with an actual meter of 5/4 the barline helps the reader see where beat 1 is.

Beat one normally gets the emphasis.

Odd meters like 5/4 or 7/8 are usually grouped into units of 3 and 2 (or 4) so there can be smaller accents after beat one. But the barline definitely helps the reader see the rhythmic pattern.

• Grouping is a very useful technique, especially for longer phrases like 25/16 in Sedi Donka. If you think of 3 as long and 2 as short, you can break 5/4 into long/short (LS), or 25/16 into 7-7-4-7, or LS LS SS LS. Feb 19, 2019 at 19:47

Depends if it's a 5-beat riff in a 4/4 framework or if it's actually in 5/4.

I'm reminded of the old theatre story about a choreographer insisting to the musical director that a dance needed music in 7/4. She counted it out. ONE two three four five six se-ven, ONE two three four five six se-ven...

• Well dancers generally tend to count to 8... XD Nov 11, 2019 at 13:04