Vehicle audio, also known as car multimedia, is equipment installed in a car or other vehicle to provide in-car entertainment and information for the occupants. Such systems are popularly known as car stereos. Until the 1950s, it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8-track tape players, Cassette decks, record players, CD players, DVD players, Blu-ray players, navigation systems, Bluetooth telephone integration and audio streaming, and smartphone controllers like CarPlay and Android Auto. Once controlled only from the dashboard using a few buttons, but today they can be controlled by steering wheel controls and voice commands. It was initially implemented for listening to music and radio but, vehicle audio is now part of car telematics, telecommunications, in-vehicle security, handsfree calling, navigation, and remote diagnostics systems. The same loudspeakers may also be used to minimize road and engine noise with active noise control, or they can also be used to augment engine sounds, for example, making a small engine sound bigger. Vehicle audio systems have begun to move to digital platforms utilizing bus networks and optical cables for signal transfer rather than traditional analog cables.
History
Radio
In 1904, before commercially viable technology for mobile radio was in place, American inventor and self-described "Father of Radio" Lee de Forest demonstrated a car radio at the 1904 Louisiana Purchase Exposition in St. Louis. Around 1920, vacuum tube technology had matured to the point where the availability of radio receivers made radio broadcasting viable. A technical challenge was that the vacuum tubes in the radio receivers required 50 to 250 volt direct current, but car batteries ran at 6V. Voltage was stepped up with a vibrator that provided a pulsating DC which could be converted to a higher voltage with a transformer, rectified, and filtered to create higher-voltage DC. In 1920 Guglielmo Marconi demonstrated a car wireless receiver in Chelmsford, Essex, England where his company had installed an experimental 6 kW longwave transmitter on 2750 meters (109 kHz). In 1924, Kelly's Motors in NSW, Australia, installed its first car radio. In 1930, the American Galvin Manufacturing Corporation marketed a Motorola-branded radio receiver for $130. The cost of these early radios was expensive, relative to the price of a car: the contemporary Ford Model A cost about $540. A Plymouth sedan, "wired for Philco Transitone radio without extra cost," was advertised in Ladies' Home Journal in 1931. In 1932 in Germany the Blaupunkt AS 5 medium wave and longwave radio was marketed for 465 Reichsmark, about one-third of the price of a small car. Because it took nearly 10 litres of space, it could not be located near the driver and was operated via a steering wheel remote control. In 1933, Crossley Motors offered a factory fitted car radio for £35. By the late 1930s, push button AM radios were considered a standard feature. In 1946, there were an estimated 9 million AM car radios in use. An FM receiver was offered by Blaupunkt in 1952. In 1953, Becker introduced the AM/FM Becker Mexico with a Variometer tuner, basically a station-search or scan function. In April 1955, the Chrysler Corporation announced that it was offering a Mopar model 914HR branded Philco all-transistor car radio, as a $150 option for its 1956 Chrysler and Imperial car models. Chrysler Corporation had decided to discontinue its all-transistor car radio option at the end of 1956, due to it being too expensive, and replaced it with a cheaper hybrid (transistors and low voltage vacuum tubes) car radio for its new 1957 car models. In 1963, Becker introduced the Monte Carlo, a tubeless solid state radio with no vacuum tubes. From 1974 to 2005, the Autofahrer-Rundfunk-Informationssystem was used by the German ARD network. Developed jointly by the Institut für Rundfunktechnik and Blaupunkt, it indicated the presence of traffic announcements through manipulation of the 57 kHz subcarrier of the station's FM signal. ARI was replaced by the Radio Data System. The AM/FM radio combined with a CD player has remained a mainstay of car audio, despite being obsolescent in non-car applications. In the 2010s, internet radio, satellite radio, streaming, and podcasting came into competition with AM/FM radio. By this time some models were offering 5.1 surround sound. In 2023, several automobile manufacturers, including Ford Motor Company, announced plans to discontinue offering the AM radio band in new vehicles, starting with the 2024 model year. Ford later reversed its announcement, with chief executive officer Jim Farley citing the importance of AM's emergency alert system. Audi, BMW, Volvo, and Tesla had already started to not offer the AM band on their entertainment systems, specifically on their electric vehicles. The previous announcement had several lawmakers introduce bipartisan legislation to require that automobile manufacturers include the AM band on their audio/entertainment systems.
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