Electric Cars Are So Quiet, They're Required By Law To Make Fake Noise

What do you do when a side benefit of a new technology turns into a safety hazard? That's a question electric and hybrid car manufacturers have been struggling with for a decade. It turns out that the high-tech engines in those vehicles are too quiet, and they're posing a risk to pedestrians. How do you fix it? Add fake engine noise.

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Why we're covering this: 

  • The amount of research that goes into something like a fake car noise is pretty amazing
  • It's one of those concepts that makes so much sense once you think about it — but how often do you think about it? 

Silent But Deadly

In November 2016, the U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA) announced a new federal safety standard that requires all newly manufactured hybrid and electric vehicles to produce audible noise at low speeds. "This is a common-sense tool to help pedestrians — especially folks who are blind or have low vision — make their way safely," said NHTSA Administrator Dr. Mark Rosekind in a statement. "With pedestrian fatalities on the rise, it is vitally important we take every action to protect the most vulnerable road users."

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The rule applies to light-duty vehicles—that is, cars that weigh 10,000 pounds or less—and says that they have to make noise when going forward or in reverse, but only at speeds up to 19 mph (30 kph). "At higher speeds, the sound alert is not required," the statement continues, "because other factors, such as tire and wind noise, provide adequate audible warning to pedestrians."

Vroom Vroom!

Luckily, the task of creating fake noise for electric vehicles is nothing new for manufacturers. Many companies have been working for a while on the problem, not only for safety reasons, but because customers associate engine noise with power. Premium sports car brands such as Porsche, Maserati, and McLaren have tried many different methods, including piping sound effects through the stereo speakers to give the driver the illusion of a big, growling engine.

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Whether the sounds happen inside the cabin or out, manufacturers put a lot of thought into the noises their cars make. What's the best noise for a futuristic car? Audi's sound engineers took three years to answer that question, developing hardware and software that would respond to their cars' speed and engine loads the way a real engine would. Manufacturers take care to tailor the sounds to each car model, and give them a pleasing fusion of old-school power and futuristic sound effects. Safety never sounded so good.

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Written by Curiosity Staff March 13, 2017

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