Equalization (audio) in the context of "Audio mixing"

An audio engineer (also known as a sound engineer or recording engineer) helps to produce a recording or a live performance, balancing and adjusting sound sources using equalization, dynamics processing and audio effects, mixing, reproduction, and reinforcement of sound. Audio engineers work on the "technical aspect of recording—the placing of microphones, pre-amp knobs, the setting of levels. The physical recording of any project is done by an engineer…"

Sound engineering is increasingly viewed as a creative profession and art form, where musical instruments and technology are used to produce sound for film, radio, television, music and video games. Audio engineers also set up, sound check, and do live sound mixing using a mixing console and a sound reinforcement system for music concerts, theatre, sports games, and corporate events.

A guitar amplifier (or amp) is an electronic device or system that strengthens the electrical signal from a pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce sound through one or more loudspeakers, which are typically housed in a wooden cabinet. A guitar amplifier may be a standalone wood or metal cabinet that contains only the power amplifier (and preamplifier) circuits, requiring the use of a separate speaker cabinet–or it may be a combo amplifier, which contains both the amplifier and one or more speakers in a wooden cabinet. There is a wide range of sizes and power ratings for guitar amplifiers, from small, lightweight practice amplifiers with a single 6-inch speaker and a 10-watt amp to heavy combo amps with four 10-inch or four 12-inch speakers and a 100-watt amplifier, which are loud enough to use in a nightclub or bar performance.

Guitar amplifiers can also modify an instrument's tone by emphasizing or de-emphasizing certain frequencies, using equalizer controls, which function the same way as the bass and treble knobs on a home stereo, and by adding electronic effects; distortion (also called overdrive) and reverb are commonly available as built-in features. The input of modern guitar amplifiers is a 1/4" jack, which is fed a signal from an electro-magnetic pickup (from an electric guitar) or a piezoelectric pickup (usually from an acoustic guitar) using a patch cord, or a wireless transmitter. For electric guitar players, their choice of amp and the settings they use on the amplifier are a key part of their signature tone or sound. Some guitar players are longtime users of a specific amp brand or model. Guitarists may also use external effects pedals to alter the sound of their tone before the signal reaches the amplifier.

An audio power amplifier (or power amp) amplifies low-power electronic audio signals, such as the signal from a radio receiver or an electric guitar pickup, to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address, home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.

The preceding stages in such a chain are low-power audio amplifiers which perform tasks like pre-amplification of the signal, equalization, mixing different input signals. The inputs can also be any number of audio sources like record players, CD players, digital audio players and cassette players. Most audio power amplifiers require these low-level inputs, which are line level.

An effects unit, effects processor, or effects pedal is an electronic device that alters the sound of a musical instrument or other audio source through audio signal processing.

Common effects include distortion/overdrive, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which modify frequency ranges; modulation effects, such as chorus, flangers and phasers; pitch effects such as pitch shifters; and time effects, such as reverb and delay, which create echoing sounds and emulate the sound of different spaces.

Live sound mixing is the blending of multiple sound sources by an audio engineer using a mixing console or software. Sounds that are mixed include those from instruments and voices which are picked up by microphones (for drum kit, lead vocals and acoustic instruments like piano or saxophone and pickups for instruments such as electric bass) and pre-recorded material, such as songs on CD or a digital audio player. Individual sources are typically equalised to adjust the bass and treble response and routed to effect processors to ultimately be amplified and reproduced via a loudspeaker system. The live sound engineer listens and balances the various audio sources in a way that best suits the needs of the event.

In sound and music, sampling is the reuse of a portion (or sample) of a sound recording in another recording. Samples may comprise elements such as rhythm, melody, speech, or sound effects. A sample might comprise only a fragment of sound, or a longer portion of music, such as a drum beat or melody. Samples are often layered, equalized, sped up or slowed down, repitched, looped, or otherwise manipulated. They are usually integrated using electronic music instruments (samplers) or software such as digital audio workstations.

A process similar to sampling originated in the 1940s with musique concrète, experimental music created by splicing and looping tape. The mid-20th century saw the introduction of keyboard instruments that played sounds recorded on tape, such as the Mellotron. The term sampling was coined in the late 1970s by the creators of the Fairlight CMI, a synthesizer with the ability to record and playback short sounds. As technology improved, cheaper standalone samplers with more memory emerged, such as the E-mu Emulator, Akai S950 and Akai MPC.