Editing Sound effect (section)

== Techniques ==
{{further|Effects unit#Techniques}}
[[File:Sfxdrumbeat.ogg|thumb|Original sound sample for comparison]]

In music and film/television production, some typical effects used in recording and amplified performances are: [[File:Echo75mil.ogg|thumb|75 millisecond echo]][[File:Flanger0.ogg|thumb|Flanger]]
[[File:Phaser0.ogg|thumb|Phaser]]
[[File:Chorus0.ogg|thumb|Chorus]]
[[File:Equalizerlow.ogg|thumb|Equalizer]]
* ''[[echo]]'' – to simulate the effect of reverberation in a large hall or cavern, one or several delayed signals are added to the original signal. To be perceived as echo, the delay has to be of order 35 milliseconds or above.  Short of actually playing a sound in the desired environment, the effect of echo can be implemented using either [[Analog signal|analog]] or [[digital delay|digital]] methods.  Analog echo effects are implemented using [[Delay (audio effect)|tape delay]] or delay lines.
* ''[[flanger]]'' – to create an unusual sound, a delayed signal is added to the original signal with a continuously variable delay (usually smaller than 10 ms).  This effect is now done electronically using [[digital signal processing|DSP]], but originally the effect was created by playing the same recording on two synchronized tape players, and then mixing the signals together.  As long as the machines were synchronized, the mix would sound more-or-less normal, but if the operator placed his finger on the flange of one of the players (hence ''flanger''), that machine would slow down and its signal would fall out-of-phase with its partner, producing a phasing effect.  Once the operator took his finger off, the player would speed up until its [[tachometer]] was back in phase with the master, and as this happened, the phasing effect would appear to slide up the frequency spectrum.  This phasing up and down the register can be performed rhythmically.
* ''[[phaser (effect)|phaser]]'' – another way of creating an unusual sound; the signal is split, a portion is [[audio filter|filtered]] with an [[all-pass filter]] to produce a phase-shift, and then the unfiltered and filtered signals are mixed. The phaser effect was originally used as a simpler implementation of the flanger effect since delays were difficult to implement with analog equipment.  Phasers are often used to give a ''synthesized'' or electronic effect to natural sounds, such as human speech.  The voice of [[C-3PO]] from ''[[Star Wars]]'' was created by taking the actor's voice and treating it with a phaser.
* ''[[chorus effect|chorus]]'' – a delayed signal is added to the original signal with a constant delay. The delay has to be short in order not to be perceived as echo, but above 5 ms to be audible.  If the delay is too short, it will destructively interfere with the un-delayed signal and create a [[flanging]] effect.  Often, the delayed signals will be slightly pitch shifted to more realistically convey the effect of multiple voices.
* [[File:Fastoverdrive.ogg|thumb|Overdrive]][[File:Pitchshift12semitones.ogg|thumb|Pitch Shift (Up 1 octave)]]''[[equalization (audio)|equalization]]'' – different frequency bands are [[Attenuation|attenuated]] or boosted to produce desired spectral characteristics. Moderate use of equalization (often abbreviated as EQ) can be used to fine-tune the tone quality of a recording; extreme use of equalization, such as heavily cutting a certain frequency can create more unusual effects.
* ''[[audio filter|filtering]]'' – Equalization is a form of filtering.  In the general sense, frequency ranges can be emphasized or attenuated using [[low-pass]], [[high-pass]], [[band-pass]] or [[band-stop]] filters.  Band-pass filtering of voice can simulate the effect of a telephone because telephones use band-pass filters.
* [[File:Modulation0.ogg|thumb|Modulation]]''[[overdriven|overdrive]]'' effects such as the use of a [[fuzz box]] can be used to produce distorted sounds, such as for imitating robotic voices or to simulate distorted radiotelephone traffic (e.g., the radio chatter between starfighter pilots in the science fiction film ''[[Star Wars (film)|Star Wars]]'').  The most basic overdrive effect involves ''clipping'' the signal when its [[absolute value]] exceeds a certain threshold.
* [[File:Compression0.ogg|thumb|Compression]]''[[audio timescale-pitch modification|pitch shift]]'' – similar to pitch correction, this effect shifts a signal up or down in pitch. For example, a signal may be shifted an octave up or down.  This is usually applied to the entire signal, and not to each note separately.  One application of pitch shifting is [[pitch correction]].  Here a musical signal is tuned to the correct pitch using digital signal processing techniques.  This effect is ubiquitous in karaoke machines and is often used to assist pop singers who sing out of tune.  It is also used intentionally for aesthetic effect in such pop songs as [[Cher]]'s "[[Believe (Cher song)|Believe]]" and [[Madonna]]'s "[[Die Another Day (song)|Die Another Day]]".[[File:Echoreverse75mil.ogg|thumb|Reverse Echo 75 Milliseconds]]
* ''[[audio timescale-pitch modification|time stretching]]'' – the opposite of pitch shift, that is, the process of changing the speed of an audio signal without affecting its pitch.
* ''[[resonators]]'' – emphasize harmonic frequency content on specified frequencies.
* ''[[robotic voice effects]]'' are used to make an actor's voice sound like a synthesized human voice.
* ''[[synthesizer]]'' – generate artificially almost any sound by either imitating natural sounds or creating completely new sounds.
* ''[[modulation]]'' – to change the frequency or amplitude of a carrier signal in relation to a predefined signal. [[Ring modulation]], also known as amplitude modulation, is an effect made famous by [[Doctor Who]]'s [[Dalek]]s and commonly used throughout sci-fi.
* ''[[Audio level compression|compression]]'' – the reduction of the dynamic range of a sound to avoid unintentional fluctuation in the dynamics.  Level compression is not to be confused with [[audio data compression]], where the amount of data is reduced without affecting the amplitude of the sound it represents.
* ''[[3D audio effect]]s'' – place sounds outside the stereo basis
* ''[[sound on sound (technique)|sound on sound]]'' – to record over a recording without erasing. Originally accomplished by disabling the tape-erase magnet. This allowed an artist to make parts of the work sound like a duet.
* ''[[reverse echo]]'' – a swelling effect created by reversing an audio signal and recording echo and/or delay whilst the signal runs in reverse. When played back forward the last echos are heard before the effected sound creating a rush-like swell preceding and during playback.{{efn|[[Jimmy Page]] of [[Led Zeppelin]] used this effect in the bridge of "[[Whole Lotta Love]]".}}