Time and Time Signatures

We've had a good look at the sound element of music — notes, and the way they're organized into scales — but, to become music, they need a chunk of time to be played in. So, before we look at the most important aspect of the sound element, chords, lets first get an idea of how that mysterious, undefinable thing we call time comes into play.

The basic units of time are 'beats' and the timeline of a piece of music is divided into 'bars' or 'measures' which consist of a certain number of beats. That number is determined by the composer of the piece and is written as the 'Time signature'. I'll use some graphics to explain, with time flowing from left → → → to right.

Time signatures are those numbers you see on sheet music at the beginning of the first line. They look like fractions. (4/4 ... 3/4 ...6/8). The top number indicates how many beats you're going to find in each measure; the bottom number tells you what kind of beats. The most common time signature is 4/4, which means 4 beats per measure, each beat being a quarter note. We humans seem to like the repetition of rhythms in groups of four.

If you read out loud the numbers below at a steady rate, stressing the 1, you'll hear the essence of two bars of 4/4. You can also listen to a few bars on the audio player.


Now, without changing the rate -- the 'tempo' -- do the same with the two measures below and you'll hear the essence of 4/4 in eighth beats and have a listen to the sound file.

4/4 in eighths

Do the same with each beat divided into three. Each beat is a 'triplet' ... this is sometimes called 12/8. Have a listen to the sound file.

4/4 in triplets, sometimes called 12/8

And, finally, we'll divide each beat into four, which means sixteenth beats. So, each quarter beat is divided into 4. Have a listen to the sound file.

4/4 in sixteenths

And so on ... we won't bother with 32nds and 64ths. The important thing to note is that it isn't the tempo that is changing, it's the number of subdivisions per beat. All these have been based on 4 beats per bar.

The next most common time signature is 3/4, otherwise known as a Waltz. So it has 3 quarter notes per bar and they can be sub-divided just like the 4/4 examples above. The example below shows 3/4 time with each beat divided into 3.

3/4, also known as a 'waltz'

Those are just the main ones. There are all kinds of time signatures, but they're all measured in the same way with that double-digit symbol: number-of-beats / kind-of-beats.