What is a… Time Signature?

Stephen Johnson gets to grips with classical music's technical terms


A time signature specifies how many beats there are in a bar, and the note values of those beats.


‘Auntie, did you feel no pain,
Falling from that apple tree?
Will you do it, please, again?
‘Cos my friend here didn’t see.’

What Harry Graham presents us with here is a piece of poetry in four-time. Each line has four strong beats: DA-de DA-de DA-de DA.

Read it aloud, and you’ll almost certainly find you space those beats equally in time, even though the final DA has no -de. If it were a piece of music you would say it was in ‘Four-four’ time.

You’d indicate this at the very beginning of the piece with the sign 4/4, the second ‘four’ signifying that the main beat is written as a ‘crotchet’ (or, in the US, a ‘quarter note’). At the end of each group of four you’d draw a vertical bar-line to indicate that the basic pulse-pattern is complete.

Now recite your favourite limerick. The rhythm should be: de DA-de-de DA-de-de DA (or DA-de). Four beats, but now each beat breaks down into a more fluent three sub-beats – or ‘triplets’.

Even though there’s still a basic four-beat pattern at work here, the time signature now reflects that subordinate triplet pattern: – three ‘quavers’ (UK) or ‘eighth-notes’ (US) times four beats = 12/8. 

However, when you recited your limerick, you probably noticed there was something a bit different about line three: de DA-de-de DA, de DA-de-de DA. Four beats, or two groups of two? If the latter, and if it were music, you’d probably put an extra bar-line right down the middle, and halve the time signature to 6/8.

If the same thing happened in line three of Harry Graham’s poem – ie if he’d written the inelegant Climb back up. Fall again – you’d halve the basic 4/4 to 2/4. 

Western music has been dominated by Four-time since the early Baroque era, but in Medieval church music patterns of three beats dominated. The usual explanation is that this symbolised the ‘perfection’ represented by the Holy Trinity.

But the appeal to composer and listener must have been more than merely abstract. Like four time it must answer to some human instinct – like the somewhat less holy Waltz (the archetypal 3/4, three-time Western dance form).

And then there’s the unsettling effect if you try any other beat pattern than two, three or four: Handel’s use of 5/8 to indicate madness in Orlando is still a tad unnerving, as is the ‘inhuman’ 5/4 march of Holst’s ‘Mars’. You can express so much in music before you even consider pitch.

One of the first things musicians learn is that metres with two or four main beats are called ‘simple’, and those with three (or other, stranger odd numbers like five or seven) are called ‘compound’. If the beat subdivides into units of two, its called ‘duple’; if into three, ‘triple’. Hence ‘simple duple’, ‘simple triple’, ‘compound duple’, and so on.

Fine, except that in all the rehearsals I’ve been to, I can’t remember anyone ever using these terms. So let’s stick with what musicians actually use. Last month we encountered crotchet/quarter-note time signatures (2/4, 3/4, 4/4 etc) and the quaver/eighth-note variety (6/8, 9/8, 12/8 etc).

There are others, but all are built on fractions or multiples of the basic 4. Sometimes the beat is a minim. Since the early Baroque era, the crotchet has dominated beat-notation, but in religious music of the medieval era – and for some time afterwards – it was the minim. 

Minim-based time signatures are indicated with a base 2: eg 2/2, 3/2, 4/2 etc. Interestingly, when more recent composers have wanted to indicate an archaic or religious quality in their music, they’ve sometimes resorted to these ‘older’-looking time signatures, as in the grand closing fugue of Mendelssohn’s Elijah.

But the choice of time signature also affects the ‘quality’ of the beat. For well over a century, the Andante introduction to the first movement of Schubert’s Great C major Symphony was thought to be in 4/4. In fact he indicated it as 2/2 (the old-fashioned symbols he used led to the confusion).

The difference is crucial. Even if the speeds of the notes are more or less identical, 4/4 saunters or tiptoes in four little beats, while 2/2 strides boldly in two big ones. 

Then there are the multiples. The sublime Arietta finale of Beethoven’s Op. 111 Piano Sonata is marked 9/16 (ie a semiquaver/16th-note beat). Its wild, jazz-like third variation is marked 12/32 – the ‘beat’ supposedly demisemiquavers, or 32nd-notes.

The result on the page is a terrifying forest of black lines and half-lines. But perhaps that’s the point: what looks like vertigo on the page translates more readily into vertigo in performance?


This article was first published in the Christmas 2012/January 2013 issue of BBC Music Magazine