Time signatures, or meters, are a way to communicate the pulse and feel of a piece of music. Musicians, dancers and listeners alike use them to interpret where the strong and weak beats lie, including their divisions. Find out the specifics of time signature in this lesson.
Time Signature Purpose and Definition
Have you ever seen one of those annoying infomercials for an exercise program? There's always some overenthusiastic instructor bouncing around, saying, 'Feel the beat!' But where is the beat? How can a composer and musician communicate something that is usually heard? The answer is time signature. A time signature, or meter, is a written indicator that shows the number of beats per measure and the type of note that carries the beat in a piece of music. The time signature also indicates the feel of a piece of music based on the divisions of the beat. While this is not the most earth-shattering piece of information, it is important in interpreting and understanding music throughout history and from around the world.
Parts of a Time Signature
Example of a quarter note
The time signature is shown at the beginning of a piece of music, right after the key signature. If you look at the time signature, you'll see that it's made up of two numbers. The bottom number shows the type of note that carries the beat. In other words, the bottom number determines which type of note we see as the pulse of the music. In this example, we see that the bottom number is four. If we imagine this as a fraction with a one on top, we can recognize this as a quarter. This means that the quarter note carries the beat.
Example of an eighth note
Let's look at another example. Here, the bottom number is eight. When we imagine it as a fraction, we get 1/8 (or an eighth), so we know that the eighth note carries the beat. The most common time signatures use four or eight as the bottom number. But you can also have two or 16 as the bottom number, since these are also types of notes. Some rebel 20th century composers like to make sure you did your math homework by using irrational meter, where the meter has a bottom number that is not a type of note, like 6, to figure out divisions of a beat. But, that's an explanation for another day.
Example of six beats per measure
The top number shows the number of beats per measure. So if we see the time signature 3/4, we know that there are three beats per measure. Here, we see a four on top, so we know that 4/4 time has four beats per measure. In this example, we know that there are six beats per measure.
Example of three eighth notes
When we combine the information given to us by these two numbers, we no longer have to guess what the beat or feel of the music will be. In a meter, like 4/4, we can see that each measure will have the equivalent of four quarter notes. The bottom number tells us that the quarter note carries the beat, and the top number tells us that we need four of them to fill the measure. In a meter like 6/8, the bottom number tells us that the eighth note carries the beat, and the top number tells us that we need six of them to fill the measure. Look at this example: how would you interpret this? If you said that the measure is filled with three eighth notes, you are correct!
Duple Meter and Triple Meter
Aside from calculating beats, time signatures can also clue us in to the feel of the music. The two basic feels are duple meter and triple meter. As you might have guessed, duple means having measure divided into two beats, or groups of two, and triple meter means a measure divided into three beats, or groups of three. Meters like 4/4, 2/4 and 6/8 are examples of duple meter, because their measures divide into two groups. Duple meter is extremely common in popular music today, in everything from rock to rap to pop to reggae. In fact, 4/4 time is so common that it's actually called 'common time' and is sometimes shown as a letter C, for common. Meters like 3/4 and 9/8 are examples of triple meter, because their measures divide into three groups. Triple meter is also used in popular music, but you probably know it better from dances like the waltz.
Simple and Compound Meter
We can even go further into interpreting the time signature by determining whether it is simple meter or compound meter. The descriptors 'simple' and 'compound' have to do with the divisions of the beat. Simple meter has a division of two parts per beat, like a pair of eighth notes. We can see this in both duple and triple meter. You can think of simple meter like bouncing a basketball; the ball is pushed down on the beat and comes back up like, '1 and 2 and 3' and so on. Compound meter, on the other hand, has a division of three parts per beat, like a triplet. Again, we can see this in both duple and in triple meter. This time, the division is '1 and a 2 and a 3' and so on. So, any meters that have a division of two are simple, and any meters that have a division of three are compound.
Sometimes, time signatures can't be defined as just simple or compound. These meters are called complex meter or odd meter. Complex time signatures have both simple and compound divisions within the same measure. We can see this in time signatures such as 5/8, where we have a division of three and a division of two. Another example is 7/8 time, where there are two simple and one compound beat. In each case, the compound and duple beats can be arranged in any order. These meters are not terribly common, unless you happen to be into Greek or Bulgarian folk dancing.
Finally, we have mixed meter. Mixed meter happens when two different meters are played in the same song. Often, this means alternating between the two time signatures. We can hear this in the song 'America' from the musical West Side Story, where the meter alternates between 6/8 and 3/4 time.
In this lesson, you learned that time signature, also called meter, tells us the number of beats per measure and the type of note that carries the beat. Duple meter has a common denominator of two beats, while triple meter has three beats. Simple time signatures divide the beat into two parts, and compound time signatures divide the beat into three parts. Complex or odd meter combines both simple and compound divisions into one measure. Lastly, mixed meter is when a song uses two different time signatures.
Once you've completed this lesson, you should be able to:
- Define what a time signature is and understand its purpose
- Explain the different parts of a time signature
- Discuss duple meter and triple meter
- Explain simple and compound meter and what you do if you can't define a time signature as simple or compound
- Define mixed meter