Sound Recording and Reproduction - Stereo and Hi-fi

Stereo and Hi-fi

See also: Stereophonic sound and High fidelity

In 1881, it was noted during experiments in transmitting sound from the Paris Opera that it was possible to follow the movement of singers on the stage if earpieces connected to different microphones were held to the two ears. This discovery was commercialized in 1890 with the Théâtrophone system, which operated for over forty years until 1932.

In 1931 Alan Blumlein, a British electronics engineer working for EMI, designed a way to make the sound of an actor in a film follow his movement across the screen. In December 1931 he submitted a patent including the idea, and in 1933 this became UK patent number 394,325. Over the next two years, Blumlein developed stereo microphones and a stereo disc-cutting head, and recorded a number of short films with stereo soundtracks.

Magnetic tape enabled the development of the first practical commercial sound systems that could record and reproduce high-fidelity stereophonic sound. The experiments with stereo during the 1930s and 1940s were hampered by problems with synchronization. A major breakthrough in practical stereo sound was made by Bell Laboratories, who in 1937 demonstrated a practical system of two-channel stereo, using dual optical sound tracks on film. Major movie studios quickly developed three-track and four-track sound systems, and the first stereo sound recording for a commercial film was made by Judy Garland for the MGM movie Listen, Darling in 1938.

The first movie commercially released with a stereo soundtrack was Walt Disney's Fantasia, released in 1940. The original 1941 release of this production used the "Fantasound" sound system. This system employed a separate film for the sound, which ran in synchronism with the film carrying the picture. On this sound film were four double-width optical soundtracks, three of which carried left, center and right audio while the fourth was a "control" track on which were recorded three tones which controlled the playback volume of the three audio channels. Because of the complex equipment required to present it, it was shown as a roadshow, but only in the United States. Regular releases of the film were on standard mono optical 35 mm stock until 1956 when the film was released with a stereo soundtrack using the "Cinemascope" four-track magnetic sound system.

German audio engineers working on magnetic tape are reported to have developed stereo recording by 1943, but it was not until the introduction of the first commercial two-track tape recorders by Ampex in the late 1940s that stereo tape recording became commercially feasible. However, despite the availability of multitrack tape, stereo did not become the standard system for commercial music recording for some years and it remained a specialist market during the 1950s. This changed after the late 1957 introduction of the "Westrex stereo phonograph disc", which used the groove format developed earlier by Blumlein. Decca Records in England came out with FFRR (Full Frequency Range Recording) in the 1940s which became internationally accepted and a worldwide standard for higher quality recordings on vinyl records. The Ernest Ansermet recording of Igor Stravinsky's Petrushka was key in the development of full frequency range records and alerting the listening public to high fidelity in 1946.

Most pop singles were mixed into monophonic sound until the mid-1960s, and it was common for major pop releases to be issued in both mono and stereo until the early 1970s. Many Sixties pop albums now available only in stereo were originally intended to be released only in mono, and the so-called "stereo" version of these albums were created by simply separating the two tracks of the master tape. In the mid Sixties, as stereo became more popular, many mono recordings (such as The Beach Boys' Pet Sounds) were remastered using the so-called "fake stereo" method, which spread the sound across the stereo field by directing higher-frequency sound into one channel and lower-frequency sounds into the other.