What Is a Rhythm Section?

The backbone of a groove

Midsection Of Person Playing Drums
Kristina Kohanova / EyeEm / Getty Images

A rhythm section is a core group of instruments within an ensemble that together play a  groove/accompaniment under a lead instrument or vocalist. Most commonly, particularly in contemporary groove-based popular music since the 1950s, these roles are the drumbeat, bass, and a chord comping parts, fulfilled by a drum set, electric bass, and guitar and/or piano/keyboard. (Some writers only include bass and drums in the rhythm section, particularly in rock "power trio" contexts.) Together, the players of these parts define the music’s characteristic metric, rhythmic, and harmonic components, which evokes and defines the style and unique character of the song or composition.

The exact instruments that constitute a rhythm section vary depending on the style and era. For example, 1940s jazz rhythm sections tended to have a small drum set, upright bass, and piano. A contemporary Afro-Cuban jazz rhythm section will likely include hand percussion in addition to the drum set. An electronica or other dance style rhythm section will typically have a drum machine, MIDI loops, or other electronic source of drumbeat sounds and electronic synths for bass and chords—possibly no acoustic instruments at all.

Because the actual instruments vary, it is useful to consider the rhythm section in terms of its instrument roles, rather than only the specific instruments fulfilling those roles. In addition, a specific instrument might fulfill multiple roles in the ensemble. A band might have a single guitar, for example, that both plays rhythm guitar parts (a rhythm section role) and also lead guitar (a melodic role).

Roles

  • The drumbeat is a recurring pattern of unpitched percussive hits. Typically, the beat includes reference to the smallest rhythmic subdivision and the pattern of accents that define the rhythmic feel characteristic of the genre. Most commonly, in a drum set, this subdivision is articulated by the hi-hat or ride cymbal. A swing beat will therefore tend to have a triplet-based pattern in the cymbals. A classic funk beat will tend to have a sixteenth-note feel. While not every subdivision will necessarily sound on every beat, it will at least reference this underlying feel to give the beat its characteristic. In addition to the beat subdivision, there will be more less emphasis on the individual metric pulses, and other patterns. A clave-based drumbeat may have a two-bar pattern, clearly organizing the characteristic 2/3 vs. 3/2 patterns intrinsic organization. So, the drumbeat’s role is essentially to define the time feel and tempo of the groove. This doesn’t mean that the drummer is the “conductor” or the “metronome,” but he or she does tend to be the defining reference point for the groove’s rhythmic undercurrent. This role may be fulfilled by a drum set, a drum machine, a hand percussion ensemble, digital loops, beat-boxing/body percussion, strummed muted guitar strings, or other percussive sound sources.
  • The bass’s primary job is to define the harmonies, and thus, the harmonic rhythm of the piece. The bass plays the primary chord notes, generally matching the root and 5 with the strong beats of the measure, such as beat 1 and 3 in 4/4 time, 1 and 4 in 6/8, and just 1 in 3/4. Usually, at each new chord, the bass will play that chord’s root, and then create a bass line designed to reinforce or arrive at the essential harmony in every new measure. The bass might “play time” (play steady notes throughout the measures) or “walk,” which is a more linear way of approaching the significant harmonic target notes. Between chord tones, the bass will play a variety of approach notes, and other articulations, such as skips. In the rhythm section context, the bass will be particularly attuned to the drummer’s kick drum, careful to “lock in” or synchronize significant rhythmic hits with that instrument, but drawing on the hi-hat’s subdivision for some of the articulations. In this way, the groove’s underlying rhythmic and harmonic structure reinforce each other. The role of the bass might be fulfilled by an upright bass (usually acoustic but sometimes electric), a bass guitar, a keyboard/synth bass sound, a tuba, a baritone saxophone, a cello, or any other low-pitched instrument.
  • The third major rhythm section role is that of the chord-comping instruments, usually rhythm guitar and piano. This role is to provide the greater harmonic context for the piece. A “comping” (accompaniment) part is essentially chords played with a repeating rhythmic structure. Because the drums play the most significant metric hits and the bass plays the most prominent chord notes (roots), the comping instruments are likely to build their parts around what’s missing: chord tones 3, 7, and tensions, and syncopated and sustained rhythms, using the drumbeat as its primary rhythmic reference. In this way, the comping instrument, bass, and drums together create a composite, each contributing a unique part to the greater whole. Typically, the comping instruments are rhythm guitar or piano, either of which can be electric or acoustic instruments. Other comping instruments include organ (e.g., the Hammond), synthesizer, accordion, vibraphone, or other instruments capable of playing chords.

    A rhythm section is part of an ensemble. To complete it, there might be a vocalist, a melodic instrument (lead guitar, saxophone, etc.), background singers, a wind section, a string section, additional percussion, an orchestra, a choir, or any combination of these players.

    Recordings