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Monaural or monophonic sound reproduction (often shortened to mono) is intended to be heard as if it were a single channel of sound perceived as coming from one position (unlike stereo, which uses two channels to convey the impression of sound coming from different places from left, middle, and right). In mono, only one loudspeaker is necessary, but, when played through multiple loudspeakers or headphones, identical signals are fed through each of the wires into each speaker, resulting in the perception of a one-channel sound, which "images" 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, customarily use multiple microphones, fed into multiple channels on a recording console, but each channel is "panned" to be in 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 in a single place in the soundstage. In some cases the multitrack source is mixed down to a one track tape becoming one signal. In the mastering stage, particularly in the days of mono records, the one-track or two-track mono master tape was then transferred to a one-track lathe intended to be used in the pressing of a monophonic record. However, today monaural recordings are usually mastered onto stereo and multitrack mediums, yet continue to retain their center-panned mono soundstage characteristics when played back. Monaural sound has been replaced by stereo sound in most entertainment applications. However, it remains the standard for radiotelephone communications, telephone networks, and audio induction loops for use with hearing aids. A few FM radio stations, particularly talk radio shows, choose to broadcast in monaural, as a monaural signal has a slight advantage in signal strength 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 in the late-19th century, until the second half of the 20th century, monaural was the rule for almost all audio recording. Monaural sound is normal on: *Phonograph cylinders *Disc records made before 1958, such as records made for playing at a speed of 78 rpm and earlier , , and 45 rpm microgroove records. *AM radio *Some FM radio stations that broadcast only spoken word or talk radio content in order to maximize their coverage area. Examples of this would be the CBC Radio One stations on the FM dial. Sometimes listeners will not be convinced that the signal is strong since there is no ST or STEREO LED lit. *Subcarrier signals for FM radio, which carry leased content such as background music for businesses or a radio reading service for the blind. Incompatible standards exist for: *Later records (monophonic records—which had almost disappeared in the United States by the end of 1967—could be played with a stereo cartridge) *Reel-to-reel audio tape recording (depending on track alignment) Compatible monaural and stereophonic standards exist for: *MiniDisc *Compact audio cassette *FM (and in rare circumstances AM radio broadcasting) *VCR formats *TV *digital audio file on many computers in many formats (WAV, MP3, etc.) No native monaural standards exist for: *8-track tape *Compact disc 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—such as John Mellencamp's 2010 album, ''No Better Than This'', recorded in mono just as the mid-20th century blues and folk records it emulated were. Some early recordings such as The Beatles first four albums - ''Please Please Me'', ''With The Beatles'', ''A Hard Day's Night'', and ''Beatles For Sale'' - 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, while the later pair 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. Many of Stanley Kubrick and Woody Allen's movies were recorded in mono because of their director's preferences. 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 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 monaural LPs 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'' album to ''The Beatles'' (commonly referred to as the "The White Album"). The set, simply called ''The Beatles in Mono'', also includes a two-disc summary of the mono singles, B-sides and EP tracks released throughout their career. Also included were five previously unreleased tracks originally mixed for a ''Yellow Submarine EP''. Bob Dylan followed suit on October 19, 2010 with ''The Original Mono Recordings'', a box set featuring the mono releases from ''Bob Dylan'' (1962) to ''John Wesley Harding'' (1967). On 21 November 2011, The Kinks' mono recordings were issued as ''The Kinks in Mono'' box set, featuring the releases of the band's albums from ''Kinks'' (1964) to ''Arthur'' (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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Monaural」の詳細全文を読む スポンサード リンク
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