Sound design for electric and hybrid cars
Tuesday, October 20, 2009 at 11:49 tagged traffic 
Electric cars are great. I would love to live in a city where people don't have to breathe exhaust gases every day. As there are more and more hybrid cars and even all-electric cars being developed, an issue comes up, one we didn't have to think about before: do they have to make a sound?
There used to be experts spending all their time researching ways to reduce the sound of cars with an old-fashioned gasoline engine. This time it's the other way around. But what is the problem exactly? Wouldn't it be nice to have a busy city center where you would only hear the sound of the people, with cars quietly moving by?
One argument often heard against this scenario is that it would be very dangerous for blind and visually impaired pedestrians. But I think it would be a problem for everybody. If you've ever rode a bike in Amsterdam, you know people will cross the street without looking. It happens again and again, every day, and it's not only drunk tourists who do this. We use or ears for many things, although we might not be aware of it.
I spoke with a Toyota Prius owner once, and he told me he didn't feel safe driving his hybrid car through a busy street at a low speed. While passing a cyclist he would step on the gas to have the gas-engine kick in, just to make sure they heard him approaching. This obviously is not the solution to this problem!
So what is the solution? As a sound designer this is a very interesting question to think about. We want a sound that is more pleasant to listen to than an ordinary gas or diesel engine, but we have to be careful it doesn't become too pleasant, as it will loose it's warning function. The right balance has to be found in timbre, pitch and loudness. And how will we react if an approaching car doesn't sound like an approaching car?
While electric car maker Tesla says not to worry about the issue too much and customers who bought their luxury Tesla Roadster find the relative quiet operation of the car very pleasant, other car manufacturers, like Nissan, consult experts to find out how to make their cars safer. The Nissan Leaf is supposed to make a high pitched sound similar to Blade Runner's flying cars.
One thing car companies should be aware about is that we're accustomed to the traditional sound of a car. If an electric car from Toyota will produce a completely different sound than a car from Nissan, it already becomes harder for us to get used to. I've heard about companies selling systems who produce sounds like a cat meowing or even a human voice. Imagine the potential noise pollution if each car would have a different warning sound. The urban soundscape is about to change, that's for sure!
Photo by Jule Berlin
Reader Comments (4)
Hi. Interesting subject. You're right this should be the opportunity to fight engine noise and work for a better acoustic environment. But i'm afraid the conclusion has already been drawn: an electric or hybrid car will have to sound like a gas car. To produce artificial engine noise is a bit ridiculous and a pity, but for security reasons obviously. Listen to this NPR programme, for instance.
Yes, very interesting subject for sure...
I remember walking in the city of Florence after visiting Venice. While the auditory soundscape of Venice is truly unique (no cars, very little trees, a lot of water so an interesting pattern of reflections) the noisy atmosphere of Florence annoyed me. The most annoying aspect was formed by the beeping electric busses. Although it is important to notice approaching busses, for me they don't have to sound like alarm clocks...
actually, i was under the impression that most of the sound produced by cars these days actually comes from the tyres on the road.
You are right Syntone. Thank you for the link, I hadn't heard that before!
@Sander: And guess what will happen if all kinds of cars will make different sounds :)
@Phill: At higher speeds, yes, but at low speeds it's still hard to hear them coming, especially in a busy city street with lots of other noises blending in.