What is a Four Bar Phrase?
A four bar phrase is the smallest measurable unit in musical composition/writing. First, what is a bar? The term bar and measure are interchangeable. See chart below:
What is seen above is 3 bars (measures) of music all separated by a bar line. A bar (measure) is a self-contained set of beats (1-2-3-4)(1-2-3). To create a four bar phrase we simply put four bars of music together. What a composer or songwriter does within those four bars is completely up to their creative process, but four bar phrasing is instinctual to music composing/writing and is seen everywhere.
Here is an example of a simple four bar phrase:
What is seen here is one chord per bar, each chord getting 4 beats (4 slash marks per measure).
Here is another example of a simple four bar phrase:
What is seen here is one chord per bar, each chord getting 3 beats (3 slash marks). In this example even though there is a different beat count per measure, the phrase is still written with four bars.
Application of Four Bar Phrasing
Here is a familiar example. This is Stevie Wonders’ “Isn’t She Lovely.” This is in 4/4 so each measure has 4 beats. This is a great example of how ingrained four bar phrasing is to any style of music. This is categorized as jazz/funk. The instrumentation is complex, there is a long harmonica solo, and the song is 5 minutes long. But the entire song is only made of these four bar phrases below:
The ‘A section’ would be the verse, made up of 2 four bar phrases. The ‘B section’ would be the chorus, also made up of two four bar phrases. The only different is in the second four bar phrase of the B section the B9 chord is repeated for two measure and the E chord is played for 7 beats before the G#7 chord is played for 1 beat (8 beats/2 bars total).
What we see here are two very simple sections (A and B), each made up of two four bar phrases. When you strip away all of the bells and whistles that make this song recognizable and unique, the foundation that holds it all up is a few four bar phrases.
Above is a four bar phrase with multiple chords per bar. The chord changes are faster and each chord has a different beat count. Even with more complex chord changes phrases are still built in four bar units. As an activity see if you can identify how many beats each chord gets from left to right.
Here are two chord charts for a widely used form, the 12 bar blues. The blues style is as old as American music itself. This is as simple as it looks, 3 four bar phrases that loop indefinitely. This style is used by countless musicians to improvise over, write new lyrics and melodies over, and can be used in as small or as big of an ensemble as one can imagine. But, just like the Stevie Wonder example, if a mile-high approach is taken to analyze this form, all that makes this style so recognizable are 3 four bar phrases with the same chords assigned to each bar no matter the key.