Audio mixing is the process by which multiple sounds are combined into one or more
audio channel
An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals or a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of ro ...
s. In the process, a source's volume level,
frequency content,
dynamics, and
panoramic position are manipulated or enhanced. This practical, aesthetic, or otherwise creative treatment is done in order to produce a finished version that is appealing to listeners.
Audio mixing is practiced for music, film, television and live sound. The process is generally carried out by a
mixing engineer operating a
mixing console
A mixing console or mixing desk is an electronic device for Audio mixing (recorded music), mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals fro ...
or
digital audio workstation
A digital audio workstation (DAW ) is an electronic device or application software used for Sound recording and reproduction, recording, editing and producing audio files. DAWs come in a wide variety of configurations from a single software pr ...
.
Recorded music
Before the introduction of
multitrack recording
Multitrack recording (MTR), also known as multitracking, is a method of sound recording developed in 1955 that allows for the separate recording of multiple sound sources or of sound sources recorded at different times to create a cohesive who ...
, all the sounds and effects that were to be part of a recording were mixed together at one time during a live performance. If the sound blend was not satisfactory, or if one musician made a mistake, the selection had to be performed over until the desired balance and performance was obtained. However, with the introduction of multitrack recording, the production phase of a modern recording has radically changed into one that generally involves three stages: recording,
overdubbing
Overdubbing (also known as layering) is a technique used in audio recording in which audio Music track, tracks that have been pre-recorded are then played back and monitored, while simultaneously recording new, doubled, or augmented tracks onto o ...
, and mixdown.
Film and television

During production dialogue recording of actors is done by a person variously known as location sound mixer, production sound or some similar designation. That person is a department head with a crew consisting of a boom operator and sometimes a cable person.
Audio mixing for film and television is a process during the
post-production stage of a
moving image program by which a multitude of recorded sounds are combined. In the editing process, the source's signal level, frequency content, dynamics, and panoramic position are commonly manipulated and effects added. In video production, this is called sweetening.
The process takes place on a mixing stage, typically in a
studio or purpose-built
theater
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors to present experiences of a real or imagined event before a live audience in a specific place, often a stage. The performers may communi ...
, once the picture elements are edited into a final version. Normally the engineers will mix four main audio elements called stems: speech (dialogue,
ADR,
voice-over
Voice-over (also known as off-camera or off-stage commentary) is a production technique used in radio, television, filmmaking, theatre, and other media in which a descriptive or expository voice that is not part of the narrative (i.e., non- ...
s, etc.),
ambience (or atmosphere),
sound effects
A sound effect (or audio effect) is an artificially created or enhanced sound, or sound process used to emphasize artistic or other content of films, television shows, live performance, animation, video games, music, or other media.
In m ...
, and music. As multi machine synchronization became available, filmmakers were able to split elements into multiple reels. With the advent of digital workstations and growing complexity, track counts in excess of 100 became common.
Dialogue intelligibility
Since the 2010s, critics and members of the audience have reported that dialogue in films tends to be increasingly more difficult to understand than in older films, to the point where viewers need to rely on
subtitles
Subtitles are texts representing the contents of the audio in a film, television show, opera or other audiovisual media. Subtitles might provide a transcription or translation of spoken dialogue. Although naming conventions can vary, caption ...
to understand what is being said. Ben Pearson of ''
SlashFilm'' attributed this to a combination of factors, only some of which can be addressed through audio mixing:
* Unintelligibility as a stylistic choice by filmmakers, particularly by
Christopher Nolan and those influenced by him
* Soft, under one's breath delivery of lines by actors, a practice particularly popular among younger actors, as opposed to the theatrical clarity of delivery previously used
* Low priority of sound recording on set, with priority given to the visual aspects of production
* Increased technological possibilities, including in post-production, no longer compel filmmakers to obtain an optimal recording on set
* The film crew's familiarity with the dialogue can lead them to overestimate its intelligibility
* Theaters play films at a lower than recommended volume to avoid excessive loudness complaints from the audience
* Different standards of compression and volume balance applied by the various
streaming platforms
* Inadequate audio remixing for films played in a
home theater setting or on mobile devices, where the audio playback capabilities of the various setups strongly differ from each other and from cinema settings
Live sound
Live sound mixing is the process of electrically blending together multiple sound sources at a live event using a
mixing console
A mixing console or mixing desk is an electronic device for Audio mixing (recorded music), mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals fro ...
. Sounds used include those from instruments, voices, and pre-recorded material. Individual sources may be
equalised and routed to
effect processors to ultimately be
amplified and reproduced via
loudspeakers
A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...
. The live sound engineer balances the various audio sources in a way that best suits the needs of the event.
References
Further reading
*Rose, Jay, ''
Producing Great Sound for Film and Video''. Focal Press, fourth edition 2014 Book info.
*
* {{cite book , title=Mixing Audio: Concepts, Practices and Tools , author=Izhaki, R. , isbn=9781136114229 , url=https://books.google.com/books?id=4WlM5vpO5QsC , date=2013 , publisher=Taylor & Francis
Audio engineering
Film sound production
Film post-production technology