Even if car doesn’t have an engine to rev, it still has to make enough noise to warn pedestrians that it’s coming. So says the National Highway Traffic Safety Administration, which just released a new rule that says all hybrid and electric vehicles have to produce an audible sound when traveling at low speeds.

Under the rule [PDF], all hybrid and electric light vehicles with four wheels and a gross vehicle weight rating — the maximum operating weight of a vehicle, including passengers, driver, and cargo — of 10,000 pounds or less will be required to make noise when going forward or backwards at speeds up to 19 miles per hour.

They’re not required to make a noise over that threshold because at higher speeds, other factors, like tire and wind noise, provide adequate audible warning to pedestrians, NHTSA explains.

This will especially help pedestrians who are blind or have low vision, potentially preventing 2,400 pedestrian injuries each year.

“We all depend on our senses to alert us to possible danger,” said U.S. Transportation Secretary Anthony Foxx. “With more, quieter hybrid and electrical cars on the road, the ability for all pedestrians to hear as well as see the cars becomes an important factor of reducing the risk of possible crashes and improving safety.”

Manufacturers have until Sept. 1, 2019, to equip all new hybrid and electric vehicles with sounds that meet the new federal safety standard, and half of new hybrid and electric vehicles must be in compliance one year before the final deadline.

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