Rock and pop rhythms Most rhythms in rock and blues are based on time with a
backbeat; however, many variations are possible. A backbeat is a
syncopated accentuation on the off beat. In a simple rhythm these are beats 2 and 4. Emphasized back beat, a feature of some African styles, defined
rhythm and blues recordings in the late 1940s and so became one of the defining characteristics of
rock and roll and much of contemporary
popular music.
Rock and pop harmony Harmonically, in rock music, the most common way to construct chord progressions is to play major and minor "
triads", each comprising a root, third and fifth note of a given
scale. An example of a major triad is C major, which contains the notes C, E and G. An example of a minor triad is the A minor chord, which includes the notes A, C and E. Interspersed are some four-note chords, which include the root, third and fifth, as well as a sixth, seventh or ninth note of the scale. The most common chord with four different notes is the
dominant seventh chord, which include a root, a major third above the root, a perfect fifth above the root and a flattened seventh. In the key of C major, the dominant seventh chord is a G7, which consists of the notes G, B, D and F.
Three-chord progressions are common in earlier pop and rock, using various combinations of the
I,
IV and
V chords, with the
twelve-bar blues particularly common. A four chord progression popular in the 1950s is I–vi–ii–V, which in the key of C major is the chords C major, A minor, D minor and G7.
Minor and
modal chord progressions such as I–VII–VI (in the key of E, the chords E major, D major, C major) feature in popular music. In
heavy metal music, rhythm guitarists often play
power chords, which feature a root note and a fifth above, or with an octave doubling the root, all without the third of the chord. Power chords are usually played with
distortion.
Arpeggios One departure from the basic strummed chord technique is to play
arpeggios, i.e. to play individual notes in a chord separately. If this is done rapidly enough, listeners will tend to hear the sequence as harmony rather than melody. Arpeggiation is often used in folk, country, and heavy metal, sometimes in imitation of older
banjo techniques. It is also prominent in 1960s pop, such as
The Animals' "
House of the Rising Sun", and
jangle pop from the 1980s onwards. Rhythm guitarists who use arpeggios often favor
semi-acoustic guitars and
twelve string guitars to get a bright, undistorted "jangly" sound. The
Soukous band
TPOK Jazz additionally featured the unique role of
mi-solo, (meaning "half solo") guitarist, playing
arpeggio patterns and filling a role "between" the lead and rhythm guitars.
Riffs In some cases, the chord progression is implied with a simplified sequence of two or three notes, sometimes called a "
riff". That sequence is repeated throughout the composition. In
heavy metal music, this is typically expanded to more complex sequences comprising a combination of chords, single notes and
palm muting. The rhythm guitar parts in compositions performed by more technically oriented bands often include riffs employing complex lead guitar techniques. In some genres, especially metal, the audio signal from the rhythm guitar's output is often subsequently run through some form of effect pedal or overdriven
guitar amplifier in order to create a thicker, crunchier sound for the palm-muted rhythms.
Interaction with other guitarists In bands with two or more guitarists, the guitarists may exchange or even duplicate roles for various songs or several
sections within a song. In those with a single guitarist, the guitarist may play lead and rhythm at numerous times or simultaneously, by overlaying the rhythm sequence with a lead line.
Crossover with keyboards Electronic
effects units such as delay pedals and reverb units enable electric guitarists to play arpeggios and take over some of the role of a synthesizer player in performing sustained soft, mellow
timbres, generally used as backing sounds. These can serve as sonic backgrounds in modern pop. Creating a pad sound differs from usual rhythm guitar roles in that it is not rhythmic. Some bands have a
synthesizer performer play pads. In bands without a synth player, a guitarist can take over this role.
Replacing lead guitar Some rhythm techniques cross over into
lead guitar playing. In guitar-bass-and-drums
power trios guitarists must double up between rhythm and lead. For instance
Jimi Hendrix combined full chords with solo
licks,
double stops and
arpeggios. In recent years, "
looping pedals" have been used to supply chord sequences or riffs over which musicians can then play the lead line, simulating the sound achieved by having two guitarists.
Equipment A rhythm guitarist usually aims to generate a strong rhythmic and chordal sound, in contrast to the lead guitarist's goal of producing sustained, often higher-pitched melody lines, that listeners can distinguish above the other instruments. As a result, rhythm and lead players often use different guitars and amplifiers. Rhythm guitarists may employ an electric
acoustic guitar or a
humbucker-equipped electric guitar for a richer and fatter output. Also, rhythm guitarists may use strings of a larger gauge than those used by lead guitarists. However, while these may be practices, they are not necessarily the rule and are subject to the style of the song and the preference of the individual guitarist. While rhythm guitarists in metal bands use distortion effects, they tend to use less of the modulation effects such as
flangers used by lead guitar players. Whereas the lead guitarist in a metal band is trying to make the solo tone more prominent, and thus uses a range of colorful effects, the rhythm guitarist is typically trying to provide a thick, solid supporting sound that blends in with the overall sound of the group. In alternative rock and post-punk, however, where the band may be aiming to create an ambient soundscape rather than an aggressive
Motörhead-style "
wall of sound", the rhythm guitarist may use flanging and delay effects to create a shimmering background, or (as in
The Smiths song "
How Soon Is Now?"), a reverberating tremolo effect. ==Jazz==