1881:
Clement Ader introduces a stereo system at the Paris Electrical
Exhibition. He broadcasts opera programs over a closed circuit wire line to a
listening booth with stereo telephones.
Late 1920s:
Engineers at Bell Labs begin experimenting with binaural
(two-channel) recordings.
1931:
A.C. Keller, a scientist at Bell Labs, develops a way to record stereo
onto a disk. He takes two recording styluses and two tone arms and hooks them up
together, producing a recording master that has two tracks on it. Later, he
figured out how to record both tracks in one groove by recording the two tracks
at a forty-five-degree angle.
1934:
Keller demonstrates stereophonic sound by playing the Philadelphia
orchestra, conducted by Leopold Stokowski, to a demonstration hall in Washington,
D.C. Three microphones spaced across the orchestra in Philadelphia were picked
up, amplified, sent over phone lines to Washington, and played back over three
corresponding loud speakers.
1940:
The first commercial use of stereo sound was Disney's Fantasia in
1940. The sound track for the film was recorded on eight separate channels,
which were mixed into three channels with a fourth control channel to enhance the
playback. "Fantasound" was duplicated in theaters with banks of speakers which
were placed behind the screen and in the auditorium to surround the audience with
sound.
Late '40s though '50s:
Small companies founded by such entrepreneurs as Avery
Fisher, Jim Lansing, Sidney Harman, Herman Scott, Amar Bose, and Saul Marantz
manufacture hi-fi stereo equipment.
1952:
Henry Kloss and Edgar Villchur create the first acoustic suspension
loudspeaker, the AR-1.
1958:
First stereo LP records released. By the late 1960s almost all new
recorded music was stereophonic.
1961:
First stereo FM radio broadcasts
1963:
Philips Corporation develops the audiocassette.
1967:
Ray Dolby develops noise reduction system.
1969:
Four-channel (Quadrophonic) stereo tapes and LPs marketed.
1975-1978:
First digital recordings made.
1980:
Portable stereo "walkman" introduced in the U.S.
1982:
FCC authorizes AM stereo broadcast, and Dolby Laboratories introduces
surround sound for home use.
1983:
First CD player made available through technology developed by Sony and
Philips, and hi-fi VCRs introduced.
- FCC authorizes multichannel TV sound broadcast; first stereo TV broadcasts.
Sales of stereo color TV receivers and adapters begin.
1986:
Stereo sound in television broadcasting available in all major U.S.
population centers.
1993:
FCC adopts signal standard for AM stereo broadcasting.
1998:
Dolby digital audio is used in High Definition Television broadcasting.
