Vehicle audio is equipment installed in acar or other vehicle to providein-car entertainment and information for the occupants. Such systems are popularly known ascar stereos. Until the 1950s, it consisted of a simpleAM radio. Additions since then have includedFM radio (1952),8-track tape players,Cassette decks,record players,CD players,DVD players,Blu-ray players,navigation systems,Bluetooth telephone integration and audiostreaming, and smartphone controllers likeCarPlay andAndroid Auto. Once controlled from the dashboard with a few buttons, they can be controlled bysteering wheel controls andvoice commands.
Initially implemented for listening to music and radio, vehicle audio is now part of cartelematics,telecommunications, in-vehicle security,handsfree calling,navigation, andremote diagnostics systems. The same loudspeakers may also be used to minimize road and engine noise withactive noise control, or they may be used to augment engine sounds, for example, making a small engine sound bigger.
In 1904, before commercially viable technology for mobile radio was in place,Americaninventor and self-described "Father of Radio"Lee de Forest demonstrated a car radio at the 1904Louisiana Purchase Exposition inSt. Louis.[1]
Around 1920,vacuum tube technology had matured to the point where the availability ofradio receivers made radio broadcasting viable.[2] A technical challenge was that the vacuum tubes in the radio receivers required 50 to 250voltdirect current, but car batteries ran at 6V. Voltage was stepped up with avibrator that provided a pulsating DC which could be converted to a higher voltage with atransformer,rectified, and filtered to create higher-voltage DC.
In 1924, Kelly's Motors in NSW, Australia, installed its first car radio.[3][4][5]
In 1930, the AmericanGalvin Manufacturing Corporation marketed aMotorola-brandedradio receiver for $130.[6] It was expensive: the contemporaryFord Model A cost $540. A Plymouth sedan, "wired for Philco Transitone radio without extra cost," was advertised inLadies' Home Journal in 1931. In 1932 in Germany theBlaupunkt AS 5medium wave andlongwave 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.[7] In 1933,Crossley Motors offered a factory fitted car radio for £35.[8] 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.[9]
AnFM 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.[10]
In April 1955, theChrysler Corporation announced that it was offering aMopar model 914HR brandedPhilco all-transistor car radio,[11] 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.[12] In 1963, Becker introduced the Monte Carlo, a tubelesssolid state radio with no vacuum tubes.[10]
From 1974 to 2005, theAutofahrer-Rundfunk-Informationssystem was used by the GermanARD network.[13] Developed jointly by theInstitut für Rundfunktechnik and Blaupunkt,[14] it indicated the presence of traffic announcements through manipulation of the 57 kHzsubcarrier of the station's FM signal.[15] ARI was replaced by theRadio Data System.[16]
The AM/FM radio combined with a CD player has remained a mainstay of car audio, despite being obsolescent in non-car applications.[17][18]
In the 2010s,internet radio,satellite radio,streaming, andpodcasting came into competition with AM/FM radio. By this time some models were offering5.1 surround sound.
In 2023, several automobile manufacturers, includingFord 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 officerJim Farley citing the importance of AM'semergency 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.[20]
Mobile players for physical media have been provided forvinyl records,8-track tapes,cassette tapes,compact discs, andMP3s. The increased sophistication of the vehicle audio system to accommodate such media has made the audio unit a common target of car break-ins, so these are equipped withanti-theft systems too.
Attempts at providing mobile play from media were first made with vinyl records, beginning in the 1950s. The first such player was offered by Chrysler as an option on 1956 Chrysler, Desoto, Dodge, and Plymouth cars. The player was developed byCBS Labs and played a limited selection of specially provided 7-inch discs at 16⅔RPM. The unit was an expensive option and was dropped after two years. Cheaper options using commonly available45 rpm records were made byRCA Victor (available only in 1961) andNorelco. All of these players required extra pressure on theneedle to avoid skipping during vehicle movement, which caused accelerated wear on the records.[21]
In 1962, Muntz introduced the Wayfarer 4-track cartridge tape player. Celebrities, including Frank Sinatra, had these units installed in their cars.
In 1965,Ford and Motorola jointly introduced the in-car8-track tape player as optional equipment for 1966 Ford car models. In 1968, a dashboard car radio with a built-incassette tape player was introduced by Philips. In subsequent years, cassettes supplanted the 8-track and improved the technology, with longer play times, better tape quality, auto-reverse, andDolby noise reduction. They were popular throughout the 1970s and 1980s. Cassette players were still found in vehicles as late as the 2005–06Honda CR-V and 2008Acura TL. There have also been vehicle audio units that accept both compact cassettes and CDs.
Pioneer introduced the CDX-1, the first carCD (compact disc) player, in 1984. It was known for its improved sound quality, instant track skipping, and the format's increased durability over cassette tapes. 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.[22] Stock and aftermarket CD players began appearing in the late 1980s, competing with the cassette. The first car with an OEM CD player was the 1987Lincoln Town Car, and the last new cars in the American market to be factory-equipped with a cassette deck in the dashboard was the 2010 Lexus SC430,[23] and the Ford Crown Victoria.[24] A car cassette adapter allowed motorists to plug in a portable music player (CD player, MP3 player) into an existing installed cassette tape deck.[25]
In the early 21st century, compact digital storage media –Bluetooth-enabled devices,thumb drives,memory cards, and dedicated hard drives – came to be accommodated by vehicle audio systems. Around this time auxiliary input jacks and USB ports were added to connectMP3 players to the vehicle's speakers. Minivans and three-row SUVs have an available rear entertainment system with aDVD player to entertain passengers.[26]
The automobile head unit became increasingly important as a housing for front andbackupdashcams,navis, and operating systems with multiple functions, such asAndroid Auto,CarPlay andMirrorLink, allowing a smartphone's music library and navigation apps to be controlled via thevehicle's infotainment system.[27] Latest models are coming equipped with features like Bluetooth technology along with HDMI port for better connectivity. Screen size varies from 5-inch to 7-inch for the double Din car stereos.[28]
The automobile sound system may be part of anactive noise control system which reduces engine and road noise for the driver and passengers. One or more microphones are used to pick up sound from various places on the vehicle, especially the engine compartment, underside, or exhaust pipes, and these signals are handled by adigital signal processor (DSP) and then sent to the loudspeakers in such a way that the processed signal reduces or cancels out the outside noise heard inside the car. An early system focused only on engine noise was developed byLotus and licensed for the 1992Nissan Bluebird models sold in Japan.[29] Lotus later teamed withHarman in 2009 to develop a more complete noise reduction system, including road and tire noise as well as chassis vibrations.[30] One benefit of active noise control is that the car can weigh less, with less sound-deadening material used, and without a heavybalance shaft in the engine. Removing the balance shaft also increases fuel efficiency.[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.[32] Other operating data may also play a part in the DSP, data such as the engine's speed in revolutions per minute (RPM) or the car's highway speed. A multiple source reduction system may reach as much as 80% of the noise removed.[citation needed]
The same system may also be used to synthesize or augment engine noise to make the engine sound more powerful to the driver.[33] For the 2015Ford Mustang EcoBoost Fastback and EcoBoost Fastback Premium, an "Active Noise Control" system was developed that amplifies the engine sound through the car speakers. A similar system is used in theF-150pickup truck.Volkswagen uses aSoundaktor, a special speaker to play sounds in cars such as theGolf GTi andBeetle Turbo.BMW plays a recorded sample of its motors through the car speakers, using different samples according to the engine's load and power.[34]
The stock system is theOEM application that the vehicle's manufacturer specified to be installed when the car was built.
Aftermarket components can also be used.
Amplifiers increase the power level of audio signals. Some head units have built-in stereo amplifiers. Other car audio systems use a separate stand-alone amplifier. Every amplifier has a rated power level sometimes noted on the head unit with the built-in amplifier, or on the label of a stand-alone unit.
Vehicles can beretrofitted or upgraded with additional, non-fixed audio systems.FM transmitters provide a way of listening to audio output from a device using the car's FM radio.[35][36]Cassette tape adapters give the ability of an auxiliary input on a car cassette deck, being able to output audio on the car stereo from a smartphone,portable CD player and any other equipment using the standardheadphone jack. There also exist cassette adapters that make use ofBluetooth.[37] Older cars that may lack Bluetooth in its stereo unit can also be fitted with a Bluetooth adapter through e.g. the car'scigarette power outlet.[38]
Newer cars that may lack a nativeCD player may also be upgraded using a portable CD player outputting through the car stereo's auxiliary port, or through Bluetooth or an FM transmitter.[39] Some companies, including car manufacturers themselves, have offered external CD players as add-ons, designed specifically for use in the car.[40]
Excessively loud sound systems in automobiles violate thenoise ordinance of municipalities, some of which have outlawed them.[41] In 2002, theU.S. Department of Justice issued a guide topolice officers on how to deal with problems associated with loud audio systems in cars.[42]
![A 1950s Philips car radio using both transistor and valves. This model used a range of valves that only required 12 volts for their plate (anode) voltage.[43]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aAutoradio_Roehre.jpg)
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Car interior | |
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Part of a series of articles oncars | |
| Instruments | |
| Controls | |
| Anti-theft | |
| Other elements | |
| Convenience | |
| Music technology | |
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| Sound recording | |
| Recording media | |
| Analog recording | |
| Playback transducers | |
| Digital audio | |
| Live music | |
| Electronic music | |
| Software | |
| Professions | |
| People and organizations | |
| Related topics | |
