Time signatures are the numbers you find at the beginning
of a piece of music just after the clef sign. These numbers tell you 2 things.
The top number tells you how many beats there are in each measure, and the
bottom number tells what kind of beats they are. For example, 4/4 means there
are 4 quarter (crotchet) notes in each measure.
There are three main categories of time signatures:
Simple Time
Compound Time
Irregular Time
In simple time the top number is usually 2, 3 or 4. With
2/4 time there are 2 beats in the bar, in 3/4 time 3 notes and as stated above
in 4/4 time 4 beats in the bar. 4/4 time can also be shown as a C symbol in the
area where the time signature is usually placed. Cut time is where there are 2
half-beat notes in the measure and this can be indicated as 2/2 or a C with a
line running down the middle of it (as if cut in half).
Compound time will be usually be indicated by a pair of
numbers where the top number is higher than 4 and divisible by 3. The most
common example of this is 6/8 time where there are 6 eighth (quaver) beats to
each measure. If the music is fast however you will often find the notes linked
in groups of 3 with notes 1 and 4 having the main emphasis. In music that is in
6/8 time you'll find 2 groups of 3 notes, 9/8 time 3 groups, and 4 groups in
12/8 time. It could also be that instead of a group of 3 quavers, the music has
dotted crotchet beats.
Irregular time signatures are identifiable as having top
numbers that are higher than 4 (as in compound time), but the bottom number is
not divisible by 3. This gives such time signatures as 5/8 or 7/4. Although
the numbers look more complicated, if you keep the general principle of the top
number and bottom number definitions in mind, you'll understand the music score
you're playing.
One thing that you should look out for is
time signature
changes occurring in the music. This isn't rare and can happen when a piece of
music starts a new section. This can happen throughout the music where the
timing changes to allow different parts of the music to take on a different
pace. What is also sometimes seem, although not as commonly, is that composers
change the timing just for one particular measure. It may not seem clear why
they have done this until you play the piece and notice how that slight time
change in the measure allows you to place emphasis on particulate notes.
Apart from the three main categories of time signature
noted above, you should also be aware that occasionally there will be no time
signature on a piece of music. This is known as free time, and may well have
the word "free" wrote down the side of the music staff. Although you may see a
pattern in the amount of notes in each measure, you won't actually have a bottom
number to tell you what kind of note the composer had in mind and so will be
free to play it as you wish.
Watch this short video to see how time
signatures work: