Most forms of music, as well as some other performing arts such as dance, include a base rhythm that sets a pace for the activity as a whole. In music, this is often set by percussion instruments, but is expressed throughout the performance as a whole.
There are a number of different ways in which rhythm can be used and defined in music. This Udemy music theory class can help you understand and read some of the different types of musical rhythms described here. If you are interested in learning about composing music, this basic music composition course can teach you everything you need to know about rhythm and much more.
Western Musical Rhythms
European and other Western music uses a time signature, or meter signature, to measure the rhythm of a particular piece of music. One of the most frequently used time signatures in rock, blues and other forms of pop music is 4:4 time, also known as common time. This means that there are four beats per measure (this is the first 4 in the signature, usually written as a numerator), and the unit being used for each beat is the quarter note (this is the second 4, or the denominator). This is the basis for a wide range of dance music and is one of the most frequently used base rhythms. Keep in mind that although the unit of measurement here is the quarter note, not all of the note lengths in a typical piece of music will be the same.
A slightly different form of 4:4 time, typically used in marches and other military music, is 2:4 time, using shorter measures than 4:4 time and therefore moving more quickly; the easy division into twos is what makes it work well for march music.
Another common rhythm used in Western dance is 3:4 time, also known as waltz time for its main use. Although more typical of older, classical music, it is often used in a number of ballad forms, being more associated with slower, more contemplative music and less obviously energetic dance forms.
6:8 time, which is a doubled version of 3:4, is used in more energetic dance music, such as polkas, jigs, and some rock pieces. In this case, the beat is based on eighth notes rather than quarter. The effect that this tends to create is to divide the measures into two set of three beats, with heavier downbeats on the first and fourth counts, creating a feeling of greater speed even when the tempo isn’t increased.
Unusual Western Examples
In most Western music, other time signatures—even “odd” signatures such as 3:4—tend to be rare in formally published music dating from before around the 19th century. Following some exceptional examples of 5:4 time, including by Tchaikovsky, twentieth century pop and rock music saw more experimentation. This can be seen in a wide range of later work by the Beatles, such as “Strawberry Fields”, and the notable Dave Brubeck Quartet album Time Out, consisting entirely of songs such as “Blue Rondo a la Turk”, in 9:8 time, and “Take Five”, one of the currently better-known examples of 5:4. This classical music survey course can expand on rhythm patterns used in earlier Western music.
Modernist classical music in particular has many examples of less conventional rhythmic structures, such as Stravinsky’s The Rite of Spring, derided by some for its lack of structure; other pieces alternate between time signatures, as indicated by notations on the musical score, or have even been left without any bar or time signatures, except on occasion as a loose guide to the musicians.
One good example of a more conventional piece with alternating rhythms is “America” from West Side Story, which uses both 6:8 and 3:4 times. Here, it is used in part as a way to shift the tempo, between quicker (6:8) and slower (3:4) triplet structures.
African Musical Rhythms
Unlike Western music, many forms of music from Africa tend to include a stronger focus on percussion. Although musical techniques in sub-Saharan Africa have traditionally been passed on orally, more recently African scholars have transcribed pieces using Western notation in order to make their music more widely available for both enjoyment and analysis.
Music from many parts of Africa, particularly drumming, can often center on the tension between two different rhythms being played by different musicians at the same time. This is known as polyrhythmic music. There is often a dominant rhythm, with potential for interplay between what can be a number of other competing rhythms. The meaning of polyrhythmic music comes from the interplay between parts, as opposed to the interplay of melody and harmony more typical of Western music. Polyrhythmic music also tends to be associated very strongly with dance, and can play an important role in the spiritual life of the broader culture.
One of the more common sub-Saharan patterns is a triplet played over the space of two beats rather than the space of one, as would be typical of Western music. This is a type of rhythmic cell also frequently used in Cuban and Afro-Caribbean music, where it is known as tresillo, having been brought by Africans in the days of the slave trade.
The tresillo is one example of a type of five-beat rhythmic pattern, known as a clave, which forms a staple of rhythmic organization throughout Afro-Cuban music. A clave can be used in a variety of time signatures, in either double- or triple-pulse patterns. Similar types of five-beat patterns can be seen in Brazilian bossa nova, where they were also brought over by African slaves. From Afro-Caribbean music, the clave rhythm spread in the twentieth century into North American jazz and popular R&B, where it is sometimes known as a Bo Diddley beat after one of the better-known practitioners (in songs like “Who Do You Love”) and can be heard in conventional pop and rock work like Buddy Holly’s “Not Fade Away”.
With some knowledge of these basics and others, not only will you be able to appreciate the music you listen to better, you will be able to start training toward working in music. A good understanding of rhythm is essential to understanding sheet music (especially if you are a drummer), as well as writing it. Even potential DJs may want to look at this course on music theory for electronic musicians