Vehicle audio
Initially implemented for listening to music and radio, vehicle audio is now part of car telematics, telecommunications, in-vehicle security, handsfree calling, navigation, and remote diagnostics systems.
[2] 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.
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.
[13] Developed jointly by the Institut für Rundfunktechnik and Blaupunkt,[14] it indicated the presence of traffic announcements through manipulation of the 57 kHz subcarrier of the station's FM signal.
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.
[19] The previous announcement had several lawmakers introduce bipartisan legislation to require that automobile manufactures include the AM band on their audio/entertainment systems.
All of these players required extra pressure on the needle to avoid skipping during vehicle movement, which caused accelerated wear on the records.
In subsequent years, cassettes supplanted the 8-track and improved the technology, with longer play times, better tape quality, auto-reverse, and Dolby noise reduction.
Car CD changers started to gain popularity in the late 1980s and continued throughout the 1990s, with the earlier devices being trunk-mounted and later ones being mounted in the head unit, some able to accommodate six to ten CDs.
[26] The automobile head unit became increasingly important as a housing for front and backup dashcams, navis, and operating systems with multiple functions, such as Android Auto, CarPlay and MirrorLink, allowing a smartphone's music library and navigation apps to be controlled via the vehicle's infotainment system.
An early system focused only on engine noise was developed by Lotus and licensed for the 1992 Nissan Bluebird models sold in Japan.
[30] One benefit of active noise control is that the car can weigh less, with less sound-deadening material used, and without a heavy balance shaft in the engine.
[31] The 2013 Honda Accord used an active noise control system, as did the 2013 Lincoln luxury line and the Ford C-Max and Fusion models.
[35] In 2002, the U.S. Department of Justice issued a guide to police officers on how to deal with problems associated with loud audio systems in cars.
