Common Time in Music Notation

Musical notes, treble clef, and common time signature made from pieces of guitar strings

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Common time is another way of notating and referring to the 4/4 time signature, which indicates that there are four quarter note beats per measure. It may be written in its fraction form of 4/4 or with a c-shaped semicircle. If this symbol has a vertical strike-through, it’s known as “cut common time.”

How Time Signatures Work

In music notation, the time signature is placed at the beginning of the staff after the clef and the key signature. The time signature indicates how many beats there are in each measure, and what the value of the beat is. The time signature is typically displayed as a fractional number — common time being one of the exceptions — where the top number indicates the number of beats per measure, and the bottom number indicates the value of the beat. For example, 4/4 means four of a beat. The bottom four symbolizes a quarter note value. So there will be four quarter-note beats per measure. However, if the time signature were 6/4, there would be six quarter-notes per measure. 

Mensural Notation and Origins of Rhythmic Value

Mensural notation was used in music notation from the late 13th century to around 1600. It comes from the word mensurata which means "measured music" and was used to bring definitions in a numerical system that could help musicians, primarily vocalists, define the proportions between note values. During its development throughout the centuries, different methods of mensural notation emerged from France and Italy, but eventually, the French system became systematically accepted across Europe. This system introduced ways of notes to be given values of units, and whether a note would be read as ternary, which was considered to be "perfect," or binary, which was considered to be "imperfect." There were no bar lines used in this type of notation, so time signatures were not yet relevant for reading music.

Development of the Common Time Symbol

When mensural notation was being used, there were symbols that indicated if the unit values of the notes were perfect or imperfect. The concept has roots in religious philosophy. A complete circle indicated a tempus perfectum (perfect time) because a circle was a symbol of completeness, whereas an incomplete circle that resembled the letter "c" indicated tempus imperfectum (imperfect time). Eventually, this led to the triple meter being represented by the circle, while imperfect time, a type of quadruple meter, was written using an incomplete, “imperfect” circle.

Today, the common time symbol represents the simplest duple time in music notation—and perhaps the most frequently used with pop musicians—which is the earlier mentioned 4/4 time signature.

Resources and Further Reading

Fox, Dan. Write It Right! Alfred Music, 1995.