Ytdyklly

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 grapsed 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?

Thanks, in advance!

It basically comes down to how the way the notes are emphasised affects how your ear hears how the beats are grouped. Listen to a piece in 5/4 - like Take Five, or the theme to Mission Impossible - and you'll hear that the beats are audibly in groups of 5. Notating the piece in 5/4 enables the first beats of the bar 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.

It's definitely for reading purposes.

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.

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.