Time Signatures (lesson)

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Hello again! In the first lesson of this series we focused on individual notes and the different lengths they could be time-wise. Now we can use this knowledge to take a step back and understand how timing for a whole song works, based on the concepts we discussed. If you are reading this part of the lesson first, I suggest you go back and review part 1, which is here.


Structure and Bars or Measures

The basic unit of time from the point of view of a song is the bar or measure (two terms for the same thing). A bar is a regular collection of notes, each of the same duration in terms of the number of notes it contains. The duration of a bar in note terms is defined at the beginning of the song in the time signature (more of which later) and each bar is assumed to contain the same number of notes unless the time signature is explicitly changed.

Generally speaking, significant things happen at the beginning of bars such as chord changes, bass drum hits and many other things. That’s not to say that these things don’t happen in many other places, rather, the bar structure is designed so that it reflects the overall rhythmic layout of the song, and a lot of these events naturally fall on the beginning and end of bars.

Given that we can write down the timing of individual notes why do we actually need bars? Well, I guess technically we don’t – you could write an entire song without bars but it would be very confusing. So among other things, breaking a song down into bars gives you an easy way of figuring out where in the song you are – it’s a lot easier to go to bar 15 than to note 127 …

Another reason for bars is that as mentioned above, the bar is the basic unit of a time signature. So if your song demands a quick (even 1 bar) change in time signature, you need to break those notes into a separate bar with its own time signature, and then have a new time signature when you want to revert back. If you didn’t do this, the feel of the song would get out of step. So a bar is also the minimal unit of time signatures.

So now we understand note durations, and that we break down songs into bars to keep things manageable – let’s look at time signatures.

Time Signatures

So what is a time signature? It is a way of describing to someone reading the music how the overall rhythm of the song fits together. If you compare say a Straussian Waltz to the average Metallica song, they sound very different. Leaving aside the obvious differences in instrumentation, the rhythmic feel of the song is also very different. This is because a waltz is in 3/4 time, and the average Metallica song is in 4/4. 3/4 and 4/4 are both examples of time signatures and they describe exactly when beats are emphasized in a song, and how long we go between down beats (or main beats). Changing a time signature can make a huge change to the mood and feel of a song.

Okay, now let’s take a look at one:


The time signature is the two numbers (both the number 4) stacked one on top of the other. This may look a bit like a fraction, but in this case, both numbers mean a different thing. When we say 4/4 or 3/4 they are pronounced as two numbers – “Four four”, or “Three four”. The top number refers to the number of beats in a bar. The bottom number tells us the type of beats that represent the timing. (It is important, that you remain aware that the type of note is just a representation; when you go on to learn topics like the speed (velocity) of music. Time signatures do not tell you how fast a piece of music should be played).

Right, so the time signature above, the 4 on top tells us that there are 4 beats in a bar. The bottom 4 (If we look at the list from the note tree, tells us that those notes are crotchets, or quarter notes. So there are 4 quarter notes in a bar. In most songs in 4/4, you can expect to find a bass drum kick on beats 1 and 3, and a snare hit on beats 2 and 4 – different time signatures would capture the feel differently and you would get corresponding drum hits on different beats of the bar.

If the time signature showed 3/4 time, you would have 3 beats in the bar, all crotchets. It would look like this:


If the time signature showed 2/4 time, you would have 2 beats in the bar, all crotchets, and it would look like bar this:


Okay so far? Theory is not so difficult really.

Simple or Compound

Right, now it's time to get into the interesting stuff. There was a specific reason why I've shown you the three bars I have, as these are the basic building blocks of music. The 4/4 bar is also known as simple quadruple (quadruple meaning that there are 4 beats in the bar. The 3/4 bar is also known as simple triple time, (triple meaning.. well I think you can guess what triple means ).

So why are these times simple?

It's all about how we split the notes up. Here is a musical score with a selection of time signatures – don’t try an play this, you’ll go blind.


Bars 1 - 3 show us the time signatures we have already discussed in action. Now, look at bar 4. It actually has the same note durations as bar 2, adding up to a total of 3 quarter notes, but now instead of playing 1 quarter note on each beat, we are now trying to cram two eighth notes into every beat. (Two notes, 3 beats, that's six notes altogether by my reckoning.)

Notice how they are grouped. In pairs. If the beats are to be divided rhythmically by splitting into halves, it's called simple time. The simple time signatures are ones like 2/4, 3/4 and 4/4.

Compound time signatures

So we've now got a bar of music, with 6 eighth notes in it. The rhythm would be “1 and 2 and 3 and” ...

There is however, a time signature, called 6/8. So isn't this the same thing? Indeed wouldn't this be a better choice? Look at bar 5. There are still 6 eighth notes, but they are grouped in threes. Brilliant for those 3 note per string scales eh? So that's it. If the beats are divided rhythmically by splitting into thirds, it's called compound time. I've provided the equivalent compound times to the ones in the first section. They are 6/8. 9/8, and 12/8. You will note that we are using dotted crotchets here – refer back to part one if you have forgotten what the dot means!

That’s it for part 2 of the lesson. In part 3 we are going to look at Odd time signatures!