Chorus effect
Encyclopedia
In music, a chorus effect (sometimes chorusing or chorused effect) occurs when individual sounds with roughly the same timbre
and nearly (but never exactly) the same pitch
converge and are perceived as one. While similar sounds coming from multiple sources can occur naturally (as in the case of a choir or string orchestra), it can also be simulated using an electronic effects unit
or signal processing device.
It is characteristic of sounds with a rich, shimmering quality that would be absent if the sound came from a single source.
The effect is more apparent when listening to sounds that sustain for longer periods of time.
The chorus effect is especially easy to hear when listening to a choir or string ensemble. A choir has multiple people singing each part (soprano
, tenor
, etc.). A string ensemble has multiple violinists and possibly multiples of other stringed instruments. When individual singers or violins play the same part, the chorus effect can be heard. Some instruments produce the effect all on their own. Examples include:
-encoded effect in a digital effect processor, or an analog effect processor. If the processor is hardware-based, it may be packaged as a foot pedal, a rack-mount
module, a table-top device, or built in to an instrument amplifier
(often an acoustic guitar amplifier or an electric guitar amplifier). Some keyboard instruments have an electronic chorus effect built in, such as some electronic pianos and some Hammond organ
s.
Regardless of the technology or form factor, the processor achieves the effect by taking an audio signal and mixing it with one or more delayed, pitch-modulated copies of itself. The pitch of the added voices is typically modulated by an LFO, which makes the overall effect similar to that of a flanger
, except with longer delays and without feedback.
Stereo chorus effect processors produce the same effect, but it is varied between the left and right channels by offsetting the delay or phase of the LFO. The effect is thereby enhanced because sounds are produced from multiple locations in the stereo field. Used on instruments like "clean" (undistorted) electric guitar and keyboards, it can yield very dreamy or ambient
sounds. Commercial chorus effect devices often include controls that enable them to be used to also produce delay, reverberation, or other related effects that use similar hardware, rather than exclusively as chorus effects.
Timbre
In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices and musical instruments, such as string instruments, wind instruments, and percussion instruments. The physical characteristics of sound that determine the...
and nearly (but never exactly) the same pitch
Pitch (music)
Pitch is an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.Pitches are compared as "higher" and "lower" in the sense associated with musical melodies,...
converge and are perceived as one. While similar sounds coming from multiple sources can occur naturally (as in the case of a choir or string orchestra), it can also be simulated using an electronic effects unit
Effects unit
Effects units are electronic devices that alter how a musical instrument or other audio source sounds. Some effects subtly "color" a sound, while others transform it dramatically. Effects are used during live performances or in the studio, typically with electric guitar, keyboard and bass...
or signal processing device.
Methods
When the effect is produced successfully, none of the constituent sounds is perceived as being out of tune.It is characteristic of sounds with a rich, shimmering quality that would be absent if the sound came from a single source.
The effect is more apparent when listening to sounds that sustain for longer periods of time.
The chorus effect is especially easy to hear when listening to a choir or string ensemble. A choir has multiple people singing each part (soprano
Soprano
A soprano is a voice type with a vocal range from approximately middle C to "high A" in choral music, or to "soprano C" or higher in operatic music. In four-part chorale style harmony, the soprano takes the highest part, which usually encompasses the melody...
, tenor
Tenor
The tenor is a type of male singing voice and is the highest male voice within the modal register. The typical tenor voice lies between C3, the C one octave below middle C, to the A above middle C in choral music, and up to high C in solo work. The low extreme for tenors is roughly B2...
, etc.). A string ensemble has multiple violinists and possibly multiples of other stringed instruments. When individual singers or violins play the same part, the chorus effect can be heard. Some instruments produce the effect all on their own. Examples include:
- PianoPianoThe piano is a musical instrument played by means of a keyboard. It is one of the most popular instruments in the world. Widely used in classical and jazz music for solo performances, ensemble use, chamber music and accompaniment, the piano is also very popular as an aid to composing and rehearsal...
- Each hammer strikes multiple strings tuned to nearly the same pitch (for all notes except the bass notes). The chorus effect is so intrinsic to the timbre of a piano that it is difficult to recognize. - 12 string guitar - Six pairs of strings tuned in octaves and unisons create a chorus effect.
- SynthesizerSynthesizerA synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...
. The effect is achieved by assigning multiple, slightly detuned oscillatorsOscillationOscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
to a voice. This is referred to as "Unison" by some manufacturers. - MandolinMandolinA mandolin is a musical instrument in the lute family . It descends from the mandore, a soprano member of the lute family. The mandolin soundboard comes in many shapes—but generally round or teardrop-shaped, sometimes with scrolls or other projections. A mandolin may have f-holes, or a single...
- 4 pairs of identically tuned strings, as opposed to octaves and unisons on the 12-string guitar.
Electronic effect
The chorus effect can be simulated by signal processing equipment. The signal processor may be software running on a computer, a ROMRead-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
-encoded effect in a digital effect processor, or an analog effect processor. If the processor is hardware-based, it may be packaged as a foot pedal, a rack-mount
19-inch rack
A 19-inch rack is a standardized frame or enclosure for mounting multiple equipment modules. Each module has a front panel that is wide, including edges or ears that protrude on each side which allow the module to be fastened to the rack frame with screws.-Overview and history:Equipment designed...
module, a table-top device, or built in to an instrument amplifier
Instrument amplifier
An instrument amplifier is an electronic amplifier that converts the often barely audible or purely electronic signal from musical instruments such as an electric guitar, an electric bass, or an electric keyboard into an electronic signal capable of driving a loudspeaker that can be heard by the...
(often an acoustic guitar amplifier or an electric guitar amplifier). Some keyboard instruments have an electronic chorus effect built in, such as some electronic pianos and some Hammond organ
Hammond organ
The Hammond organ is an electric organ invented by Laurens Hammond in 1934 and manufactured by the Hammond Organ Company. While the Hammond organ was originally sold to churches as a lower-cost alternative to the wind-driven pipe organ, in the 1960s and 1970s it became a standard keyboard...
s.
Regardless of the technology or form factor, the processor achieves the effect by taking an audio signal and mixing it with one or more delayed, pitch-modulated copies of itself. The pitch of the added voices is typically modulated by an LFO, which makes the overall effect similar to that of a flanger
Flanging
Flanging is an audio effect produced by mixing two identical signals together, with one signal delayed by a small and gradually changing period, usually smaller than 20 milliseconds. This produces a swept comb filter effect: peaks and notches are produced in the resultant frequency spectrum,...
, except with longer delays and without feedback.
Stereo chorus effect processors produce the same effect, but it is varied between the left and right channels by offsetting the delay or phase of the LFO. The effect is thereby enhanced because sounds are produced from multiple locations in the stereo field. Used on instruments like "clean" (undistorted) electric guitar and keyboards, it can yield very dreamy or ambient
Ambient music
Ambient music is a musical genre that focuses largely on the timbral characteristics of sounds, often organized or performed to evoke an "atmospheric", "visual" or "unobtrusive" quality.- History :...
sounds. Commercial chorus effect devices often include controls that enable them to be used to also produce delay, reverberation, or other related effects that use similar hardware, rather than exclusively as chorus effects.