Audio feedback
Encyclopedia
Audio feedback is a special kind of positive feedback
which occurs when a sound loop exists between an audio input (for example, a microphone
or guitar pickup) and an audio output (for example, a loudspeaker
). In this example, a signal received by the microphone is amplified
and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. This is a good example of positive feedback
. The frequency
of the resulting sound is determined by resonance frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them.
, namely that, with sufficiently high gain, a stable oscillation
can (and usually will) occur in a feedback loop whose frequency is such that the phase delay is an integer
multiple of 360 degree
s and the gain
at that frequency is equal to 1. If the gain is increased until it is greater than 1 for some frequency, then it will be equal to 1 at a nearby frequency, and the system will start to oscillate at that frequency at the merest input excitation, that is to say: sound will be produced without anyone actually playing. This is the principle upon which electronic oscillator
s are based; although in that case the feedback loop is purely electronic, the principle is the same. If the gain is large, but slightly less than 1, then high-pitched slowly decaying feedback tones will be created, but only with some input sound.
The first academic work on acoustical feedback was done by Dr. C. Paul Boner beginning in 1962. Dr. Boner reasoned that when feedback happened, it did so at one precise frequency. He also reasoned that you could stop it by inserting a very narrow notch filter
at that frequency in the loudspeaker
's signal chain
. He worked with Gifford White, founder of White Instruments to hand craft notch filters for specific feedback frequencies in specific rooms. Dr. Boner was responsible for establishing basic theories of acoustic feedback, room-ring modes, and room-sound system equalizing techniques.
.
and should stay out of the maximum sensitivity
of each other, ideally at a direction of cancellation. Public address
speakers often achieve directivity in the mid and treble region (and good efficiency
) via horn systems. Sometimes the woofers have a cardioid
characteristic.
Professional setups circumvent feedback by placing the main speakers a far distance from the band or artist, and then having several smaller speakers known as monitors
pointing back at each band member, but in the opposite direction to that in which the microphones are pointing. This allows independent control of the sound pressure levels for the audience and the performers.
If monitors are oriented at 180 degrees to the microphones that are their sources, the microphones should have a cardioid
pickup pattern. Super- or hypercardioid patterns are suitable if the monitor speakers are located at a different angle on the back side of the microphones, they also better cancel reverberations coming from elsewhere. Almost all microphones for sound reinforcement are directional.
s is not ideally flat. This leads to acoustical feedback at the frequency with the highest loop gain, which may be much higher than the average gain over all frequencies (resonance
). It is therefore helpful to apply some form of equalization
to reduce the gain of this frequency.
Feedback can be reduced manually by "ringing out
" a microphone. The sound engineer can increase the level of a microphone or guitar pickup until feedback occurs. The engineer can then turn down frequency on a band equalizer preventing feedback at that pitch but allowing maximum volume. Professional sound engineers can "ring out" microphones and pick-ups by ear but most use a real time analyzer connected to a microphone to show the ringing frequency.
To avoid feedback, automatic anti-feedback devices can be used. (In the marketplace these go by the name "feedback destroyer" or "feedback eliminator".) Some of these work by shifting the frequency slightly, resulting in a "chirp"-sound instead of a howling sound due to the upshifting the frequency of the feedback. Other devices use sharp notch-filters to filter out offending frequencies. Adaptive algorithms are often used to automatically tune these notch filters.
, Johnny "Guitar" Watson and Guitar Slim
who all independently recorded and published music featuring that effect. According to Allmusic's Richie Unterberger
, the very first use of feedback on a rock record is the song "I Feel Fine
" by The Beatles
, recorded in 1964. The Who
's 1965 hits "Anyway, Anyhow, Anywhere
" and "My Generation
" featured feedback manipulation by Pete Townshend
, with an extended solo in the former and the shaking of his guitar in front of the amplifier to create a throbbing noise in the latter. Canned Heat
's Fried Hockey Boogie (off of their 1968 album Boogie with Canned Heat
) also featured guitar feedback produced by Henry Vestine
during his solo to create a highly amplified distorted boogie style of feedback. In 1963, the teenage Brian May
and his father custom-built his signature guitar Red Special
, which was purposely designed to feedback.
Feedback was used extensively after 1965 by The Monks
, Jefferson Airplane
, The Velvet Underground
and the Grateful Dead
, who included in many of their live shows a segment named Feedback, a several-minutes long feedback-driven improvisation. Feedback has since become a striking characteristic of rock music, as electric guitar
players such as Jeff Beck
, Pete Townshend
and Jimi Hendrix
deliberately induced feedback by holding their guitars close to the amplifier
. Lou Reed
created his 1975 album Metal Machine Music
entirely from loops of feedback played at various speeds. A perfect example of feedback can be heard on Jimi Hendrix
's performance of Can You See Me? at the Monterey Pop Festival
. The entire guitar solo was created using amplifier feedback.
compositions, it was contemporary American composer Robert Ashley
who first used acoustic feedback as sound material in his work The Wolfman (1964). Steve Reich
makes extensive use of audio feedback in his work Pendulum Music
(1968) by swinging a series of microphones back and forth in front of their corresponding amplifiers.
melded the rock-feedback tradition with a compositional/classical approach (notably covering Reich's "Pendulum Music"), and guitarist/producer Steve Albini
's group Big Black
also worked controlled feedback into the makeup of their songs. With the alternative rock
movement of the 1990s, feedback again saw a surge in popular usage by suddenly mainstream acts like Nirvana
, the Red Hot Chili Peppers
,Guitarist John Frusciante
is well-known for his use of feedback on stage and Chili Peppers song Emmit Remmus is one of the few tracks on the 90's that the regular riff was with feedback. Rage Against the Machine
Rage Against the Machine's guitarist Tom Morello
performs an entire guitar solo by purposefully creating audio feedback on the song "Sleep Now in the Fire
" with the aid of a tremolo bar and toggle switch. Used in this fashion, one has some control over the feedback's frequency and amplitude as the guitar strings (or other stringed instrument) form a filter
within the feedback path and one can easily and rapidly "tune" this filter, producing wide ranging effects. A more extreme example can be found on the album Absolutego
by the Japanese band Boris
, featuring a full 65 minutes of heavy guitar feedback and bass drone. and The Smashing Pumpkins
.The Smashing Pumpkins often used feedback during solos and intros of their songs.
, such as a delay pedal or effect fed back into a mixing console
. The feedback can be controlled by using the fader to determine a volume level.
Positive feedback
Positive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that responds to a perturbation in a way that reduces its effect is...
which occurs when a sound loop exists between an audio input (for example, a microphone
Microphone
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
or guitar pickup) and an audio output (for example, a loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
). In this example, a signal received by the microphone is amplified
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. This is a good example of positive feedback
Positive feedback
Positive feedback is a process in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that responds to a perturbation in a way that reduces its effect is...
. The frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
of the resulting sound is determined by resonance frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them.
History and theory
The conditions for feedback follow the Barkhausen stability criterionBarkhausen stability criterion
The Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. It was put forth in 1921 by German physicist Heinrich Georg Barkhausen...
, namely that, with sufficiently high gain, a stable oscillation
Oscillation
Oscillation 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...
can (and usually will) occur in a feedback loop whose frequency is such that the phase delay is an integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...
multiple of 360 degree
Degree (angle)
A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
s and the gain
Gain
In electronics, gain is a measure of the ability of a circuit to increase the power or amplitude of a signal from the input to the output. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It may also be defined on a logarithmic scale,...
at that frequency is equal to 1. If the gain is increased until it is greater than 1 for some frequency, then it will be equal to 1 at a nearby frequency, and the system will start to oscillate at that frequency at the merest input excitation, that is to say: sound will be produced without anyone actually playing. This is the principle upon which electronic oscillator
Electronic oscillator
An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in innumerable electronic devices...
s are based; although in that case the feedback loop is purely electronic, the principle is the same. If the gain is large, but slightly less than 1, then high-pitched slowly decaying feedback tones will be created, but only with some input sound.
The first academic work on acoustical feedback was done by Dr. C. Paul Boner beginning in 1962. Dr. Boner reasoned that when feedback happened, it did so at one precise frequency. He also reasoned that you could stop it by inserting a very narrow notch filter
Band-stop filter
In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter...
at that frequency in the loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
's signal chain
Signal chain
Signal chain, or signal-processing chain is a term used in signal processing and mixed-signal system design to describe a series of signal-conditioning electronic components that receive input in tandem, with the output of one portion of the chain supplying input to the next...
. He worked with Gifford White, founder of White Instruments to hand craft notch filters for specific feedback frequencies in specific rooms. Dr. Boner was responsible for establishing basic theories of acoustic feedback, room-ring modes, and room-sound system equalizing techniques.
Prevention
Most audio feedback results in a high-pitched squealing noise familiar to those who have listened to bands at house parties, and other locations where the sound setup is less than ideal. Usually this occurs when live microphones are pointed in the general direction of the output speakers. There are various methods used to minimize feedback—to maximize gain before feedbackGain before feedback
In live sound mixing, gain before feedback is a practical measure of how much a microphone can be amplified in a sound reinforcement system before causing audio feedback. In audiology, GBF is a measure of hearing aid performance...
.
Distance
To keep the maximal loop gain under 1, the amount of sound energy that is fed back to the microphones has to be as small as possible. As sound pressure falls off with 1/r with respect to the distance r in free space or up to a distance known as reverberation distance in closed spaces (and the energy density with 1/r²), it is important to keep the microphones at a large enough distance from the speaker systems.Directivity
Additionally, the loudspeakers and microphones should have non-uniform directivityDirectivity
In electromagnetics, directivity is a figure of merit for an antenna. It measures the power density the antenna radiates in the direction of its strongest emission, versus the power density radiated by an ideal isotropic radiator radiating the same total power.An antenna's directivity is a...
and should stay out of the maximum sensitivity
Sensitivity (electronics)
The sensitivity of an electronic device, such as a communications system receiver, or detection device, such as a PIN diode, is the minimum magnitude of input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria.Sensitivity is...
of each other, ideally at a direction of cancellation. Public address
Public address
A public address system is an electronic amplification system with a mixer, amplifier and loudspeakers, used to reinforce a sound source, e.g., a person giving a speech, a DJ playing prerecorded music, and distributing the sound throughout a venue or building.Simple PA systems are often used in...
speakers often achieve directivity in the mid and treble region (and good efficiency
Energy conversion efficiency
Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.-Overview:...
) via horn systems. Sometimes the woofers have a cardioid
Cardioid
A cardioid is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It is therefore a type of limaçon and can also be defined as an epicycloid having a single cusp...
characteristic.
Professional setups circumvent feedback by placing the main speakers a far distance from the band or artist, and then having several smaller speakers known as monitors
Foldback (sound engineering)
Foldback is the use of rear-facing heavy-duty loudspeakers known as monitor speaker cabinets on stage during live music performances. The sound is amplified with power amplifiers or a public address system and the speakers are aimed at the on-stage performers rather than the audience...
pointing back at each band member, but in the opposite direction to that in which the microphones are pointing. This allows independent control of the sound pressure levels for the audience and the performers.
If monitors are oriented at 180 degrees to the microphones that are their sources, the microphones should have a cardioid
Cardioid
A cardioid is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It is therefore a type of limaçon and can also be defined as an epicycloid having a single cusp...
pickup pattern. Super- or hypercardioid patterns are suitable if the monitor speakers are located at a different angle on the back side of the microphones, they also better cancel reverberations coming from elsewhere. Almost all microphones for sound reinforcement are directional.
Frequency response
Almost always, the natural frequency responses of sound reinforcement systemSound reinforcement system
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience...
s is not ideally flat. This leads to acoustical feedback at the frequency with the highest loop gain, which may be much higher than the average gain over all frequencies (resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
). It is therefore helpful to apply some form of equalization
Equalization
Equalization, is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications. The circuit or equipment used...
to reduce the gain of this frequency.
Feedback can be reduced manually by "ringing out
Ringing out
Ringing out is a process in audio engineering used to prevent audio feedback and maximize volume. It involves a sound technician raising the slider controls on a mixing desk to cause an audio system to feedback. Once feedback occurs, the technician uses the graphic equalizer to pull back the...
" a microphone. The sound engineer can increase the level of a microphone or guitar pickup until feedback occurs. The engineer can then turn down frequency on a band equalizer preventing feedback at that pitch but allowing maximum volume. Professional sound engineers can "ring out" microphones and pick-ups by ear but most use a real time analyzer connected to a microphone to show the ringing frequency.
To avoid feedback, automatic anti-feedback devices can be used. (In the marketplace these go by the name "feedback destroyer" or "feedback eliminator".) Some of these work by shifting the frequency slightly, resulting in a "chirp"-sound instead of a howling sound due to the upshifting the frequency of the feedback. Other devices use sharp notch-filters to filter out offending frequencies. Adaptive algorithms are often used to automatically tune these notch filters.
Early examples in popular music
While audio feedback is usually undesirable, it has entered into musical history as a desired effect beginning in the 1950s with Albert CollinsAlbert Collins
Albert Collins was an American electric blues guitarist and singer whose recording career began in the 1960s in Houston and whose fame eventually took him to stages across the US, Europe, Japan and Australia...
, Johnny "Guitar" Watson and Guitar Slim
Guitar Slim
Eddie Jones , better known as Guitar Slim, was a New Orleans blues guitarist, from the 1940s and 1950s, best known for the million-selling song, produced by Johnny Vincent at Specialty Records, "The Things That I Used to Do"...
who all independently recorded and published music featuring that effect. According to Allmusic's Richie Unterberger
Richie Unterberger
Richie Unterberger is a US author and journalist whose focus is popular music and travel writing.-Life and writing:Having worked as a DJ at WXPN in Philadelphia, he started reviewing records for Op magazine in 1983...
, the very first use of feedback on a rock record is the song "I Feel Fine
I Feel Fine
"I Feel Fine" is a riff-driven rock song written by John Lennon and released in 1964 by The Beatles as the A-side of their eighth British single. The song is notable for the use of feedback on a recording for the first time by any musician...
" by The Beatles
The Beatles
The Beatles were an English rock band, active throughout the 1960s and one of the most commercially successful and critically acclaimed acts in the history of popular music. Formed in Liverpool, by 1962 the group consisted of John Lennon , Paul McCartney , George Harrison and Ringo Starr...
, recorded in 1964. The Who
The Who
The Who are an English rock band formed in 1964 by Roger Daltrey , Pete Townshend , John Entwistle and Keith Moon . They became known for energetic live performances which often included instrument destruction...
's 1965 hits "Anyway, Anyhow, Anywhere
Anyway, Anyhow, Anywhere
"Anyway, Anyhow, Anywhere" was a single released by The Who in 1965. It features call-and-response lyrics and some of the first ever recorded guitar feedback. The song was composed by guitarist Pete Townshend and vocalist Roger Daltrey, the only time they wrote together...
" and "My Generation
My Generation
My Generation is the debut album by the English rock band The Who, released by Brunswick Records in the United Kingdom in December 1965. In the United States it was released by Decca Records as The Who Sings My Generation in April 1966, with a different cover and a slightly altered track...
" featured feedback manipulation by Pete Townshend
Pete Townshend
Peter Dennis Blandford "Pete" Townshend is an English rock guitarist, vocalist, songwriter and author, known principally as the guitarist and songwriter for the rock group The Who, as well as for his own solo career...
, with an extended solo in the former and the shaking of his guitar in front of the amplifier to create a throbbing noise in the latter. Canned Heat
Canned Heat
Canned Heat is a blues-rock/boogie rock band that formed in Los Angeles, California in 1965. The group has been noted for its own interpretations of blues material as well as for efforts to promote the interest in this type of music and its original artists...
's Fried Hockey Boogie (off of their 1968 album Boogie with Canned Heat
Boogie with Canned Heat
Boogie with Canned Heat is the second album by Canned Heat, released in 1968. Unlike their debut, it features mostly original material. It included the top 10 hit "On the Road Again," one of their best known songs. "Amphetamine Annie," a warning about the dangers of amphetamine abuse, also...
) also featured guitar feedback produced by Henry Vestine
Henry Vestine
Henry Charles Vestine a.k.a. "The Sunflower", was an American guitar player known mainly as a member of the band Canned Heat. He was with the group from its start in 1966 to July 1969...
during his solo to create a highly amplified distorted boogie style of feedback. In 1963, the teenage Brian May
Brian May
Brian Harold May, CBE is an English musician and astrophysicist most widely known as the guitarist and a songwriter of the rock band Queen...
and his father custom-built his signature guitar Red Special
Red Special
The Red Special is an electric guitar owned by Queen guitarist Brian May and custom-built by May and his father. The Red Special is also sometimes named in reviews as the Fireplace or the Old Lady, both nicknames used by May when referring to the guitar. A guitar that would define May's signature...
, which was purposely designed to feedback.
Feedback was used extensively after 1965 by The Monks
The Monks
Monks are a garage rock band, formed by American GIs who were based in Germany in the mid to late 1960s. They reunited in 1999 and have continued to play concerts, although no new studio recordings have been made...
, Jefferson Airplane
Jefferson Airplane
Jefferson Airplane was an American rock band formed in San Francisco in 1965. A pioneer of the psychedelic rock movement, Jefferson Airplane was the first band from the San Francisco scene to achieve mainstream commercial and critical success....
, The Velvet Underground
The Velvet Underground
The Velvet Underground was an American rock band formed in New York City. First active from 1964 to 1973, their best-known members were Lou Reed and John Cale, who both went on to find success as solo artists. Although experiencing little commercial success while together, the band is often cited...
and the Grateful Dead
Grateful Dead
The Grateful Dead was an American rock band formed in 1965 in the San Francisco Bay Area. The band was known for its unique and eclectic style, which fused elements of rock, folk, bluegrass, blues, reggae, country, improvisational jazz, psychedelia, and space rock, and for live performances of long...
, who included in many of their live shows a segment named Feedback, a several-minutes long feedback-driven improvisation. Feedback has since become a striking characteristic of rock music, as electric guitar
Electric guitar
An electric guitar is a guitar that uses the principle of direct electromagnetic induction to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so it is amplified before sending it to a loudspeaker...
players such as Jeff Beck
Jeff Beck
Geoffrey Arnold "Jeff" Beck is an English rock guitarist. He is one of three noted guitarists to have played with The Yardbirds...
, Pete Townshend
Pete Townshend
Peter Dennis Blandford "Pete" Townshend is an English rock guitarist, vocalist, songwriter and author, known principally as the guitarist and songwriter for the rock group The Who, as well as for his own solo career...
and Jimi Hendrix
Jimi Hendrix
James Marshall "Jimi" Hendrix was an American guitarist and singer-songwriter...
deliberately induced feedback by holding their guitars close to the amplifier
Guitar amplifier
A guitar amplifier is an electronic amplifier designed to make the signal of an electric or acoustic guitar louder so that it will produce sound through a loudspeaker...
. Lou Reed
Lou Reed
Lewis Allan "Lou" Reed is an American rock musician, songwriter, and photographer. He is best known as guitarist, vocalist, and principal songwriter of The Velvet Underground, and for his successful solo career, which has spanned several decades...
created his 1975 album Metal Machine Music
Metal Machine Music
Metal Machine Music, subtitled *The Amine β Ring, is the fifth solo album by Lou Reed. It was originally released as a double album by RCA Records in 1975...
entirely from loops of feedback played at various speeds. A perfect example of feedback can be heard on Jimi Hendrix
Jimi Hendrix
James Marshall "Jimi" Hendrix was an American guitarist and singer-songwriter...
's performance of Can You See Me? at the Monterey Pop Festival
Monterey Pop Festival
The Monterey International Pop Music Festival was a three-day concert event held June 16 to June 18, 1967 at the Monterey County Fairgrounds in Monterey, California...
. The entire guitar solo was created using amplifier feedback.
Examples in modern classical music
Though closed circuit feedback was a prominent feature in many early experimental electronic musicElectronic music
Electronic music is music that employs electronic musical instruments and electronic music technology in its production. In general a distinction can be made between sound produced using electromechanical means and that produced using electronic technology. Examples of electromechanical sound...
compositions, it was contemporary American composer Robert Ashley
Robert Ashley
Robert Ashley , is a contemporary American composer, best known for his operas and other theatrical works, many of which incorporate electronics and extended techniques. Along with Gordon Mumma, Ashley was also a major pioneer of audio synthesis.Ashley was born in Ann Arbor, Michigan...
who first used acoustic feedback as sound material in his work The Wolfman (1964). Steve Reich
Steve Reich
Stephen Michael "Steve" Reich is an American composer who together with La Monte Young, Terry Riley, and Philip Glass is a pioneering composer of minimal music...
makes extensive use of audio feedback in his work Pendulum Music
Pendulum Music
"Pendulum Music " is the name of a work by Steve Reich, involving suspended microphones and speakers, creating phasing feedback tones. The piece was composed in August 1968 and revised in May 1973....
(1968) by swinging a series of microphones back and forth in front of their corresponding amplifiers.
Contemporary uses
Audio feedback became a signature feature of many underground rock bands during the 1980s. American noise-rockers Sonic YouthSonic Youth
Sonic Youth is an American alternative rock band from New York City, formed in 1981. The current lineup consists of Thurston Moore , Kim Gordon , Lee Ranaldo , Steve Shelley , and Mark Ibold .In their early career, Sonic Youth was associated with the No Wave art and music scene in New York City...
melded the rock-feedback tradition with a compositional/classical approach (notably covering Reich's "Pendulum Music"), and guitarist/producer Steve Albini
Steve Albini
Steven Frank Albini is an American singer, songwriter, guitarist, audio engineer and music journalist. He was a member of Big Black, Rapeman, and Flour, and is currently a member of Shellac...
's group Big Black
Big Black
Big Black was an American punk rock band from Evanston, Illinois, active from 1981 to 1987. Founded by singer and guitarist Steve Albini, the band's initial lineup also included guitarist Santiago Durango and bassist Jeff Pezzati, both of Naked Raygun...
also worked controlled feedback into the makeup of their songs. With the alternative rock
Alternative rock
Alternative rock is a genre of rock music and a term used to describe a diverse musical movement that emerged from the independent music underground of the 1980s and became widely popular by the 1990s...
movement of the 1990s, feedback again saw a surge in popular usage by suddenly mainstream acts like Nirvana
Nirvana (band)
Nirvana was an American rock band that was formed by singer/guitarist Kurt Cobain and bassist Krist Novoselic in Aberdeen, Washington in 1987...
, the Red Hot Chili Peppers
Red Hot Chili Peppers
Red Hot Chili Peppers is an American rock band, formed in Los Angeles in 1983. The group's musical style primarily consists of rock with an emphasis on funk, as well as elements from other genres such as punk, hip hop and psychedelic rock...
,Guitarist John Frusciante
John Frusciante
John Anthony Frusciante is an American guitarist, singer, songwriter, record and film producer. He is best known as the former lead guitarist of the rock band Red Hot Chili Peppers, with whom he had been for a number of years and recorded five studio albums...
is well-known for his use of feedback on stage and Chili Peppers song Emmit Remmus is one of the few tracks on the 90's that the regular riff was with feedback. Rage Against the Machine
Rage Against the Machine
Rage Against the Machine is an American rock band from Los Angeles, California. Formed in 1991, the group's line-up consists of vocalist Zack de la Rocha, bassist and backing vocalist Tim Commerford, guitarist Tom Morello and drummer Brad Wilk...
Rage Against the Machine's guitarist Tom Morello
Tom Morello
Thomas Baptiste "Tom" Morello is a Grammy Award-winning American guitarist best known for his tenure with the bands Rage Against the Machine, Audioslave, his acoustic solo act The Nightwatchman, and his newest group, Street Sweeper Social Club...
performs an entire guitar solo by purposefully creating audio feedback on the song "Sleep Now in the Fire
Sleep Now in the Fire
"Sleep Now in the Fire" is the fifth track from the 1999 album The Battle of Los Angeles by the band Rage Against the Machine. It was released as a single in 2000. The song contains lyrics about greed, such as the conquest of Native Americans, Christopher Columbus' voyage by Nina, the Pinta, and...
" with the aid of a tremolo bar and toggle switch. Used in this fashion, one has some control over the feedback's frequency and amplitude as the guitar strings (or other stringed instrument) form a filter
Audio filter
An audio filter is a frequency dependent amplifier circuit, working in the audio frequency range, 0 Hz to beyond 20 kHz. Many types of filters exist for applications including graphic equalizers, synthesizers, sound effects, CD players and virtual reality systems.Being a frequency dependent...
within the feedback path and one can easily and rapidly "tune" this filter, producing wide ranging effects. A more extreme example can be found on the album Absolutego
Absolutego
Absolutego is the debut album by Japanese experimental doom band Boris. It was released in 1996 by Fangs Anal Satan. This album shows a primitive sort of inspiration from the Melvins. Excluding the Merzbow collaboration Sun Baked Snow Cave, it's the only "one-long-song" Boris album that isn't...
by the Japanese band Boris
Boris (band)
is a Japanese experimental rock band, known for often combining and switching between different music genres including drone metal, sludge metal, noise rock, psychedelic rock, ambient and pop...
, featuring a full 65 minutes of heavy guitar feedback and bass drone. and The Smashing Pumpkins
The Smashing Pumpkins
The Smashing Pumpkins are an American alternative rock band that formed in Chicago, Illinois in 1988. Formed by Billy Corgan frontman and James Iha , the band has included Jimmy Chamberlin , D'arcy Wretzky , and currently includes Jeff Schroeder Mike Byrne , and Nicole Fiorentino The Smashing...
.The Smashing Pumpkins often used feedback during solos and intros of their songs.
Marketing
The principle of feedback is used in many guitar sustain devices. Examples include handheld devices like the EBow, built-in guitar pickups that increase the instrument's sonic sustain, string drivers mounted on a stand such as the Guitar Resonator, and sonic transducers mounted on the head of a guitar. Intended closed-circuit feedback can also be created by an effects unitEffects 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...
, such as a delay pedal or effect fed back into a mixing console
Mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
. The feedback can be controlled by using the fader to determine a volume level.
External links
- Sound Improving Means and Method, U.S. Patent No. 3,624,298
- C. Paul Boner, PhD., early pioneer in studying feedback.
- In Memorium Charles Paul Boner