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Monaural or monophonic sound reproduction (often shortened to mono) is sound intended to be heard as if it were emanating from one position. This contrasts with stereophonic sound or ''stereo'', which uses two separate audio channels to reproduce sound from two microphones on the right and left side, which is reproduced with two separate
loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
s to give a sense of the direction of sound sources. In mono, only one
loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
is necessary, but, when played through multiple loudspeakers or headphones, identical
signals In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...
are fed to each speaker, resulting in the perception of one-channel sound "imaging" in one sonic space between the speakers (provided that the speakers are set up in a proper symmetrical critical-listening placement). Monaural recordings, like stereo ones, typically use multiple microphones fed into multiple channels on a recording console, but each channel is " panned" to the center. In the final stage, the various center-panned signal paths are usually mixed down to two identical tracks, which, because they are identical, are perceived upon playback as representing a single unified signal at a single place in the soundstage. In some cases, multitrack sources are mixed to a one-track tape, thus becoming one signal. In the mastering stage, particularly in the days of mono
records A record, recording or records may refer to: An item or collection of data Computing * Record (computer science), a data structure ** Record, or row (database), a set of fields in a database related to one entity ** Boot sector or boot record, ...
, the one- or two-track mono master tape was then transferred to a one-track
lathe A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to c ...
used to produce a master disc intended to be used in the pressing of a monophonic record. Today, however, monaural recordings are usually mastered to be played on stereo and multi-track formats, yet retain their center-panned mono soundstage characteristics. Monaural sound has largely been replaced by
stereo Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration ...
sound in most entertainment applications, but remains the standard for
radiotelephone A radiotelephone (or radiophone), abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to '' radiotelegraphy'', which is radio transmission of telegrams (mes ...
communications,
telephone A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. A telephone converts sound, typically and most efficiently the human voice, into e ...
networks, and
audio induction loop Audio induction loop systems, also called audio-frequency induction loops (AFILs) or hearing loops, are an assistive listening technology for individuals with reduced ranges of hearing. A hearing loop consists of one or more physical loop of cab ...
s for use with
hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss. Hearing aids are classified as medical devices in most countries, and regulated by the respective regulations. Small audio amplifiers su ...
s.
FM radio FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is cap ...
stations broadcast in stereo, while most
AM radio AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...
stations broadcast in mono. (Although an AM stereo broadcast standard exists, few AM stations are equipped to use it.) A few FM stations—notably
talk-radio Talk radio is a radio format containing discussion about topical issues and consisting entirely or almost entirely of original spoken word content rather than outside music. Most shows are regularly hosted by a single individual, and often featur ...
stations—choose to broadcast in monaural because of the slight advantage in
signal strength In telecommunications, particularly in radio frequency engineering, signal strength refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those us ...
and
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
the standard affords over a stereophonic signal of the same power.


History

While some experiments were made with stereophonic recording and reproduction from the early days of the
phonograph A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, or more recently a turntable, is a device for the mechanical and analogu ...
in the late-19th century, monaural was the rule for almost all
audio recording Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording te ...
until the second half of the 20th century. Monaural sound is normal on: *
Phonograph cylinder Phonograph cylinders are the earliest commercial medium for recording and reproducing sound. Commonly known simply as "records" in their era of greatest popularity (c. 1896–1916), these hollow cylindrical objects have an audio recording engra ...
s *
Gramophone records A phonograph record (also known as a gramophone record, especially in British English), or simply a record, is an analog sound storage medium in the form of a flat disc with an inscribed, modulated spiral groove. The groove usually starts near ...
made before 1958, such as those made for playing at 78
rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...
and earlier , and 45 rpm microgroove records *
AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmis ...
*Some
FM radio FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is cap ...
stations that broadcast only spoken-word or
talk-radio Talk radio is a radio format containing discussion about topical issues and consisting entirely or almost entirely of original spoken word content rather than outside music. Most shows are regularly hosted by a single individual, and often featur ...
content (in order to maximize their coverage area) *
Subcarrier A subcarrier is a sideband of a radio frequency carrier wave, which is modulated to send additional information. Examples include the provision of colour in a black and white television system or the provision of stereo in a monophonic radio broa ...
signals for FM radio, which carry leased content such as
background music Background music (British English: piped music) is a mode of musical performance in which the music is not intended to be a primary focus of potential listeners, but its content, character, and volume level are deliberately chosen to affect behav ...
for businesses or a
radio reading service A radio reading service or reading service for the blind is a public service of many universities, community groups and public radio stations, where a narrator reads books, newspapers and magazines aloud for the benefit of the blind and vision-imp ...
*Background music services such as
Seeburg 1000 The Seeburg 1000 Background Music System is a phonograph designed and built by the Seeburg Corporation to play background music from special 16 RPM vinyl records in offices, restaurants, retail businesses, factories and similar locations. Seeburg ...
; satellite broadcasts by
Muzak Muzak is an American brand of background music played in retail stores and other public establishments. The name has been in use since 1934, and has been owned by a division or subsidiary of one or another company ever since. In 1981, Westingho ...
, and some
public address systems A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
Incompatible standards exist for: *Later vinyl records (although monophonic records—which had almost disappeared in the United States by the end of 1967—could be played with a stereo
cartridge Cartridge may refer to: Objects * Cartridge (firearms), a type of modern ammunition * ROM cartridge, a removable component in an electronic device * Cartridge (respirator), a type of filter used in respirators Other uses * Cartridge (surname), a ...
) *
Reel-to-reel audio tape recording Reel-to-reel audio tape recording, also called open-reel recording, is magnetic tape audio recording in which the recording tape is spooled between reels. To prepare for use, the ''supply reel'' (or ''feed reel'') containing the tape is plac ...
(depending on track alignment) Compatible monaural and stereophonic standards exist for: *
MiniDisc MiniDisc (MD) is an erasable magneto-optical disc-based data storage format offering a capacity of 60, 74, and later, 80 minutes of digitized audio. Sony announced the MiniDisc in September 1992 and released it in November of that year fo ...
*
Compact audio cassette The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens ...
* FM (and, in rare circumstances, AM) radio broadcasting *
VCR A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recording. ...
formats * TV * Digital audio files on many computers in many formats (
WAV Waveform Audio File Format (WAVE, or WAV due to its filename extension; pronounced "wave") is an audio file format standard, developed by IBM and Microsoft, for storing an audio bitstream on PCs. It is the main format used on Microsoft Wind ...
,
MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Origin ...
, etc.) No native monaural standards exist for: *
8-track tape The 8-track tape (formally Stereo 8; commonly called eight-track cartridge, eight-track tape, and eight-track) is a magnetic tape sound recording technology that was popular from the mid-1960s to the early 1980s, when the compact cassette, wh ...
*
Compact disc The compact disc (CD) is a Digital media, digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. In August 1982, the first compact disc was manufactured. It was then rele ...
In those formats, the mono-source material is presented as two identical channels, thus being technically stereo. At various times artists have preferred to work in mono, either in recognition of the technical limitations of the equipment of the era or because of simple preference (this can be seen as analogous to filmmakers working in
black and white Black-and-white (B&W or B/W) images combine black and white in a continuous spectrum, producing a range of shades of grey. Media The history of various visual media began with black and white, and as technology improved, altered to color. ...
). An example is
John Mellencamp John J. Mellencamp (born October 7, 1951), previously known as Johnny Cougar, John Cougar, and John Cougar Mellencamp, is an American singer-songwriter. He is known for his catchy brand of heartland rock, which emphasizes traditional instrument ...
's 2010 album '' No Better Than This'', recorded in mono to emulate mid-20th century blues and folk records. Some early recordings such as
The Beatles The Beatles were an English Rock music, rock band, formed in Liverpool in 1960, that comprised John Lennon, Paul McCartney, George Harrison and Ringo Starr. They are regarded as the Cultural impact of the Beatles, most influential band of al ...
' first four albums (''
Please Please Me ''Please Please Me'' is the debut studio album by the English rock band the Beatles. Produced by George Martin, it was released on EMI's Parlophone label on 22 March 1963 in the United Kingdom, following the success of the band's first two s ...
'', ''
With the Beatles ''With the Beatles'' is the second studio album by the English rock band the Beatles. It was released in the United Kingdom on 22 November 1963 on Parlophone, eight months after the band's debut ''Please Please Me''. Produced by George Martin ...
'', '' A Hard Day's Night'', ''
Beatles for Sale ''Beatles for Sale'' is the fourth studio album by the English rock band the Beatles. It was released on 4 December 1964 in the United Kingdom on EMI's Parlophone label. The album marked a departure from the upbeat tone that had characterised ...
'') were re-released in the CD era as monophonic in recognition of the fact that the source tapes for the earliest recordings were two-track, with vocals on one track and instruments on the other (even though this was only true on the first two albums, while the latter two had been recorded on four-track). This was actually intended to provide flexibility in producing a final mono mix, not to provide a stereo recording, although because of demand this was done anyway, and the early material was available on vinyl in both mono and stereo formats. In the 1960s and 1970s, it was common in the pop world for stereophonic versions of mono tracks to be generated electronically using filtering techniques to attempt to pick out various instruments and vocals; but these were often considered unsatisfactory, owing to the artifacts of the conversion process. Directors
Stanley Kubrick Stanley Kubrick (; July 26, 1928 – March 7, 1999) was an American film director, producer, screenwriter, and photographer. Widely considered one of the greatest filmmakers of all time, his films, almost all of which are adaptations of nove ...
and
Woody Allen Heywood "Woody" Allen (born Allan Stewart Konigsberg; November 30, 1935) is an American film director, writer, actor, and comedian whose career spans more than six decades and multiple Academy Award-winning films. He began his career writing ...
, among others, preferred to record their films' sound tracks in mono. Monaural LP records were eventually phased out and no longer manufactured after the early 1970s, with a few exceptions. For example, Decca UK had a few double issues until the end of 1970 – the last one being Tom Jones's "I Who Have Nothing"; in
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
records were released in both mono and stereo as late as 1972. During the 1960s it was common for albums to be released as both mono and stereo LPs, occasionally with slight differences between the two (again, detailed information of The Beatles' recordings provides a good example of the differences). This was because many people owned mono record players that were incapable of playing stereo records, as well as the prevalence of AM radio. Because of the limited quantities pressed and alternative mixes of several tracks, the monaural versions of these albums are often valued more highly than their stereo LP counterparts in record-collecting circles today. On 9 September 2009, The Beatles re-released a remastered box set of their mono output spanning the ''
Please Please Me ''Please Please Me'' is the debut studio album by the English rock band the Beatles. Produced by George Martin, it was released on EMI's Parlophone label on 22 March 1963 in the United Kingdom, following the success of the band's first two s ...
'' album to ''
The Beatles The Beatles were an English Rock music, rock band, formed in Liverpool in 1960, that comprised John Lennon, Paul McCartney, George Harrison and Ringo Starr. They are regarded as the Cultural impact of the Beatles, most influential band of al ...
'' (commonly called "The White Album"). The set, simply called ''
The Beatles in Mono ''The Beatles in Mono'' is a boxed set compilation comprising the remastered monaural recordings by the Beatles. The set was released on compact disc on 9 September 2009, the same day the remastered stereo recordings and companion '' The Beat ...
'', also includes a two-disc summary of the mono singles, B-sides and EP tracks released throughout their career. Also included were five tracks originally mixed for an unissued mono '' Yellow Submarine'' EP.
Bob Dylan Bob Dylan (legally Robert Dylan, born Robert Allen Zimmerman, May 24, 1941) is an American singer-songwriter. Often regarded as one of the greatest songwriters of all time, Dylan has been a major figure in popular culture during a career sp ...
followed suit on 19 October 2010 with ''
The Original Mono Recordings ''The Original Mono Recordings'' is a box set compilation album of recordings by Bob Dylan, released in October 2010 on Legacy Recordings, catalogue 88697761042. It consists of Dylan's first eight studio albums in mono on nine compact discs, the ...
'', a box set featuring the mono releases from ''
Bob Dylan Bob Dylan (legally Robert Dylan, born Robert Allen Zimmerman, May 24, 1941) is an American singer-songwriter. Often regarded as one of the greatest songwriters of all time, Dylan has been a major figure in popular culture during a career sp ...
'' (1962) to ''
John Wesley Harding ''John Wesley Harding'' is the eighth studio album by American singer-songwriter Bob Dylan, released on December 27, 1967, by Columbia Records. Produced by Bob Johnston, the album marked Dylan's return to semi-acoustic instrumentation and folk ...
'' (1967). On 21 November 2011,
The Kinks The Kinks were an English rock band formed in Muswell Hill, north London, in 1963 by brothers Ray and Dave Davies. They are regarded as one of the most influential rock bands of the 1960s. The band emerged during the height of British rhythm ...
' mono recordings were issued as ''The Kinks in Mono'' box set, featuring the releases of the band's albums from ''
Kinks The Kinks were an English rock band formed in Muswell Hill, north London, in 1963 by brothers Ray and Dave Davies. They are regarded as one of the most influential rock bands of the 1960s. The band emerged during the height of British rhythm ...
'' (1964) to ''
Arthur Arthur is a common male given name of Brittonic languages, Brythonic origin. Its popularity derives from it being the name of the legendary hero King Arthur. The etymology is disputed. It may derive from the Celtic ''Artos'' meaning “Bear”. An ...
'' (1969), with three additional CDs of non-album tracks that appeared as singles or EP tracks. When the initial run of the box set sold out, no more were pressed, unlike the Beatles and Dylan sets.


Compatibility between mono and stereo sound

Sometimes ''mono sound'' or ''monaural'' can simply refer to a merged pair of stereo channels - also known as "collapsed stereo" or "folded-down stereo". Over time some devices have used mono sound amplification circuitry with two or more speakers since it can cut the cost of the hardware. Some consumer electronics with stereo RCA outputs have a microswitch in the red RCA output (i.e., the right stereo channel) that disables merging of stereo sound into the white (left stereo channel) RCA output. Common devices with this are
VCR A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recording. ...
s,
DVD The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...
/
Blu-ray player The Blu-ray Disc (BD), often known simply as Blu-ray, is a Digital media, digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and c ...
s, information appliances,
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of sign ...
es, and the like.
Video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can be played with a game controller. These may be home video game console, home consoles, which are generally placed i ...
s sometimes have male RCA ends of cables with a proprietary multi-A/V plug on the other end, which prevents automatic stereo merging unless adapters are used. Disadvantages of merged stereo involve phase cancellations that may have the effect of muffling the final sound output. If channels are merged after being sent through a power amplifier but before being connected to a loudspeaker, it places more stress on the
loudspeaker A loudspeaker (commonly referred to as a speaker or speaker driver) is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often simply referred to as a "speaker" or " ...
. It has usually been the practice in recording studios to make separate mixes for mono recordings (rather than folded-down stereo-to-mono), so that the final mono master will avoid the pitfalls of collapsed stereo. In video games, merging stereo to mono sound prevents player from discerning what direction distant SFX are coming from, and reverse stereo has a similar setback too. Having an array of loudspeakers connected to their own amplifier outputs can mitigate issues with the electrical load for a single loudspeaker coil and allow the listener to perceive an "image" of sound in the free space between the speakers.


Mirrored mono

Mirrored mono sound is the opposite of merged stereo, since it can be a case where media with mono sound that stereo playback devices automatically mirror it with are played on both channels of the receiver. It can also mean having a mono input mixed down to stereo amplification circuitry, or a mono system with a headphone output compatible with stereo
headphones Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an au ...
. An example of an application where both merged stereo and mirror mono apply is when a
compact audio cassette The Compact Cassette or Musicassette (MC), also commonly called the tape cassette, cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. Invented by Lou Ottens ...
respectively plays back "summed" stereo channels on a mono reading head, and when a compact cassette recorded with mono sound is played back with a stereo tape head. Other instances of "mirrored mono" also include using the right stereo channel in lieu of a "left" one (or vice versa) where both channels are wired to mirror only one.


Both

Instances of both "merged stereo" and "mirrored mono" can occur when the stereo channels are merged to a mono system with stereo headphone compatibility or when a mono system has "twin speakers" (or "pseudo-stereo"). Other applications that involve mirrored mono with merged stereo occur when MONO is available as an internal feature of a device that can toggle between STEREO and MONO, for instance many
FM radio FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is cap ...
s are capable of toggling between MONO and STEREO in a way where stereo can both MERGE into mono, and then MIRROR between both stereo speakers. This tactic can also be used on other devices, of which computer software and some
video game Video games, also known as computer games, are electronic games that involves interaction with a user interface or input device such as a joystick, controller, keyboard, or motion sensing device to generate visual feedback. This fee ...
s will have a feature that will allow STEREO or MONO for the soundtrack, in which sometimes this can facilitate MERGING stereo internally to spare one from using a Y adapter with LEFT and RIGHT RCA plugs when using mono equipment, such as
guitar amplifier 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 a ...
s.


Native stereo equipment with mono-only features

Some TV/VCR combo decks on the market had stereo TV functionality with "twin speakers", whereas the VCR feature was only mono, which is typical of "consumer-grade VCRs" from decades ago. Some of these devices even had front RCA inputs for composite video (yellow), and mono audio (white) in which many of these devices didn't even have a right-channel RCA plug (red) even if it was just for "merging" stereo into mono for mono soundtracks to be recorded onto videotapes. This is odd since one would think that a "right channel" would be included for A/V in on a TV which had MTS stereo TV sound on its tuner. Some stereo receivers will also include mono microphone inputs.


See also

*
Stereophonic sound Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration ...
*
Binaural recording Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments. This effect is ...
Sound Sound technology ja:ステレオ#モノラル再生 pl:Monofonia {{Sound-tech-stub