Monday, March 7, 2011

Bar Lines, Bars, & Time Signatures

When you look at sheet music, you will notice that there are vertical lines running through the treble and bass staff as well as numbers after the clef. These vertical lines are called a bar line while the space between 2 of these lines is called the bar or measure. The image below shows you an example of bar lines and bar on the treble staff. 

There are several different types of bar lines that tell you what to do when you reach it while playing. Below is an image of different bar lines and the details of each bar line.

Single bar line is the standard bar line seen in all music pieces. These bar lines separate the number of beats that are in a bar according to the time signature.

Double bar line is used to separate two sections or phrases of music. It can also be used at changes in key signature or major changes in style or tempo. Key signatures define the prevailing key of the music that follows. I will go into more detail about key signatures in the later lessons.

Start Repeat and End Repeat bar lines are rather obvious in that any notes that are between these 2 bar lines are to be repeated more than once. If there is no Start repeat sign, the End repeat sign sends the pianist back to the start of the piece or the nearest double bar. An example is shown below.

Final bar line is where the music concludes and you stop playing.

I will now go into time signatures. The time signature tells you how much beats are in the bar. Time signatures tend to be represented by 2 numbers; one at the top and one at the bottom (as illustrated in the image below). The top number tells us how many beats are in a bar while the bottom number tells us the note value that represents one beat (the "beat unit"). For example if there is a 1 on the bottom means that a whole note gets only 1 beat, a 2 on the bottom means that you are counting half notes while a 4 on the bottom means that the quarter note will be worth one beat. This example is shown in the image below. I will go into detail about whole notes, half notes and quarter notes in the next lesson.

Note that the red arrow tells you where each beat is counted.

There are various types of time signatures and they depend on whether the music follows simple rhythms or involves unusual shifting tempos. Some time signatures shown below include the following: the simple time signatures such as 3/4 or 4/4, the compound ones like 9/8, the complex ones (e.g., 5/4 or 7/8), the mixed ones (e.g., 5/8, 3/8 or 6/8, 3/4), the additive ones (e.g., (3+2+3)/8), the fractional ones (e.g., 2½/4), and the irrational meters (e.g., 3/10 or 5/24).

Now we can determine how many beats are in a bar in your music sheet. I'll go into a few examples of them. The time signature 3/4 tells us that there are 3 beats in a bar while 4/4 has 4 beats in a bar. The 4/4 time signature can also be expressed with the sign C and is called Common time. The most common simple time signatures seen in most music pieces are 2/4, 3/4, and 4/4, which can also be called simple duple time, simple triple time and simple quadruple time respectively.

Below are several time signatures, can you tell me how many beats are in each bar for these signatures?

The next lesson will go into the different notes and rests available, what they mean and how to play them.


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