In 1930, the Radio Manufacturers Association lobbied that backseat passengers were more of a driver distraction than a car radio; listening to the radio, they claimed, was safer than looking in the rear view mirror. Some strongly opposed the industry's claims, arguing car radios were distracting and hazardous. Illinois, Massachusetts, New York, New Jersey and Ohio state legislatures all considered implementing car radio fines, and in 1935 Connecticut legislators actually did introduce a bill that would have placed a steep fine on radio installation — $50 in 1935, which is about $850 today. Others considered making car radio installation a crime [sources: Novak, Bureau of Labor Statistics]. It wasn't until the 1939, though, that anyone actually studied whether a correlation between car radios and car crashes existed: Car radios played little to no role in car accidents, determined the Princeton Radio Research Project [source: Bijsterveld].
Decades ago, the Society of Automotive Engineers advised drivers follow the 15-second rule. That is, a driver can be distracted with an in-car activity, such as talking to passengers or retrieving an item from the glove compartment, for up to 15 seconds before the task becomes a visual distraction and becomes unsafe. Fifteen seconds, can you imagine? Every five seconds at 55 mph a car travels about 360 feet (107 meters), which is the length of a football field. Now multiply that by three — that's a lot of distance covered without the driver's attention and focus on driving. Today, both the National Highway Traffic Safety Administration (NHTSA) and the U.S. Department of Transportation (DOT) recommend no in-car activity take more than two seconds, else it becomes a distraction [sources: Parkview Trauma Centers, Barth].
We'd be surprised if a present-day car rolled off the assembly line without at least a radio installed, if not a sleek audio system. Today, too, car audio systems are considered to be among low-level distractions (along with eating and drinking) that, combined, are responsible for distracting us about one-third of the time we spend behind the wheel. In fact any time you fiddle with a device — or reach for a french fry — while you're driving, you take your attention away from the road [sources: DMV, University of Groningen].
Although listening to music while driving has long been considered a driving distraction, hearing the music without handling a media player or touching the car audio controls, has been found, actually, to contradict that long-held belief. Listening to music — just listening — it turns out, may help drivers stay focused on the road during long trips on monotonous highways [source: University of Groningen]. So why, then, are we wonky about the radio volume when it comes time to look for an upcoming exit sign or when we're approaching an unfamiliar destination? It has to do with the demands on our ability to concentrate, and the limitations of the human brain.