Mobile  systems

Car stereos generally have 4 speakers. The left and right channels supply a pair of speakers. The left stereo channel drives left front and left rear speakers; right stereo channel drives right front and right rear speakers. The balance control adjusts ratio of sound volume between left and right channels for both the front and rear speaker sets. The other control adjusts ratio of sound volume between the front and rear sets. This gives impression of surround sound. But it is not a true quadraphonic system as there are only 2 independent sound channels: left- front and rear and right -front and rear.An automotive hi-fi stereo system has an AM/FM receiver and a cassette tape player. More expensive systems incorporate CD players. It’s essential to remember that both tapes and CDs are heat-sensitive and should not be stored in the car or truck that may become hot. On a sunny summer day, interior of a closed parked car can rise to a level enough to damage tapes and CDs.

Car stereo systems can relieve some of tedium of long driving trips. But the sound can present a safety hazard if volume is excessive. Loud music obscures outside traffic noises, including sirens and honking horns. A headset, if worn by driver, presents an even fatal danger. In many states, it is illegal to wear a headset at the time driving a motor vehicle.