The Sound of Silence

The philosopher asks, if a car zips through a forest, and there's no gasoline combusting under its hood, would it make a sound?

Electric vehicles make almost no sound. That’s a hugely important advantage after a century of loud internal combustion engines stealing what brief snatches of quiet we find on walks or bike rides. What a delightful extra added to the ecologically sound vehicles.

But that’s a problem too. The internal combustion engine is not only a cost-effective motive force generator; it’s a safety feature. You can hear an approaching car. You can’t really hear an approaching EV, unless the environment around is really quiet. If you’re sight-impaired, this is no laughing matter.

When I’m out walking our dog on the trail around our neighborhood lake, I don’t hear the bike riders approaching me from behind. Some will shout out “passing on the right,” which usually startles me right out of my skin. A little, handle bar-mounted bell works well too. But what if they were traveling faster? Like a car??

On the Chevy Volt, engineers designed what can be called a horn belch, activated by tugging on the turn-signal bar on the steering wheel. Automobile manufacturers are looking for other ways to solve this problem such as generating some constant sound, whether it’s an imitation of an internal combustion engine, a low hum or something else.

Expect the government may require electric cars and gasoline-electric hybrids to emit some type of noise at low speeds, when their battery-driven motors usually run silent. The promised rules—aimed at making the vehicles safer for vision-impaired pedestrians and others who rely on aural cues—have launched auto makers on a quest for the perfect sound.

On my visits to Tokyo, I noticed that the opening and closing of the subway-train doors was signaled by the sound of birds chirping. How perfectly Japanese and how elegant.  Among the sounds considered for electric cars are noises reminiscent of jet engines, bells, birds, flying saucers and revved-up sports cars.

In developing their electric car, the Leaf, Nissan Motor Co. marketers initially saw the false-sound feature as a branding opportunity, a chance to create a distinctive sound, like a Jetsons jet pack, that would identify an approaching vehicle as a Leaf.

How would you approach this design challenge when it comes to electric vehicles? Would you look for a solution that was always-on (like the low hum)? Would you favor a user-generated response — a bell or belch? Would you deploy sensors to signal the car to make a noise?

Originally written on September 24, 2011.