Asymmetrical time signatures (also sometimes called complex or irregular time signatures in music theory) generally contain five or seven beats, compared to the traditional two‐, three‐, and four‐beat measure groupings (as part of simple and compound time signatures). Asymmetrical time signatures are common in traditional music from around the world, including in European folk music and in Eastern (particularly Indian) popular and folk music.
When you play or hear a piece of music with an asymmetrical time signature, you notice that the pulse of the song feels and sounds quite a bit different from music written under simple or compound time signatures. Music with 5/4, 5/8, and 5/16 time signatures is usually divided into two pulses — either two beats plus three beats, or vice versa. The stress pattern doesn’t have to repeat itself from measure to measure; the only constant is that each measure still contains five beats.
For example, here, the pulse is defined by the placements of the half notes in each grouping, making the stresses fall on the third beat in the first measure and on the fourth beat in the second measure, like this:
ONE two THREE four five | ONE two three FOUR five
The beaming of the eighth notes shows where the stresses are to occur — on the first eighth note of each set of beamed notes. Here’s what it looks like if you say it out loud:
ONE two THREE four five | ONE two three FOUR five
Music with 7/4, 7/8, and 7/16 time signatures looks like the music below. Again, the stress patterns don’t have to stay the same from one measure to the next.
If the time signature were 7/4, you would count off the beat like this:
ONE two three FOUR five six seven | ONE two three four FIVE six seven
Here’s how you count off a time signature of 7/8:
ONE two three FOUR five SIX seven | ONE two THREE four FIVE six seven
Asymmetrical time signatures are considered “complex” only from a Western point of view. These irregular time signatures have been used regularly throughout history and around the world, including in ancient Greece and Persia. They also can still be heard in Bulgarian folk music.
Modern Western composers and ensembles as diverse as Steve Albini, Beck, Dave Brubeck, June of 44, Andrew Lloyd webber, Frank Zappa, Pink Floyd, Yo‐Yo Ma, Bobby McFerrin, and Stereolab have all used asymmetrical time signatures in their music. A whole genre of rock, called math rock, is based on using complex time signatures, such as 7/8, 11/8, 13/8, and so on, in order to break away from the 4/4 time that’s the standard in rock.