When I get into my car and shut the door, its closing makes a solid kind of sound. I had never given much thought to it, thinking that the sound of closing was an incidental byproduct of the door’s design and manufacture. It appears that I was mistaken. In an article on the sounds that cars make, John Seabrook writes that much thought goes into creating that particular sound.

The engine’s sound isn’t the only thing that the engineers work on. Many prospective buyers’ first experience of a car or a truck is the CLICK ker-CHUNK that the driver’s-side door makes when they close it, followed by a faint harmonic shiver given off by the vehicle’s metal skin. The door’s weight, latches, and seals are carefully calibrated to create a psychoacoustic experience that conveys comfort, safety, and manufacturing expertise.

Who knew?

The focus on the sounds that cars make has increased with the advent of electric vehicles because while at high speed they make roughly the same wind and road noise as other cars, at low speeds they are so quiet that they pose a danger to pedestrians (especially the blind) and cyclists who depend upon the sounds of cars to know what is happening around them. As a result, back in 2010 congress passed the Pedestrian Safety Enhancement Act.

As a result of the legislation, every E.V. and hybrid manufactured since 2020 and sold in the U.S. must come equipped with a pedestrian-warning system, also known as an acoustic vehicle alerting system (avas), which emits noises from external speakers when the car is travelling below eighteen and a half miles per hour. (Similar regulations apply in Europe and Asia.)

The Pedestrian Safety Enhancement Act called for a “sound or set of sounds for all vehicles of the same make and model” but did not specify in detail what requirements the sounds should be like and that took another six years.

With the normal internal combustion engines, most of the effort went into suppressing engine and road noise as much as possible, with the exception of so-called ‘muscle cars’ where the driver wants a growl to denote power and speed. With electric vehicles, they have to add sounds and as a result, car manufacturers have a wide range to choose from and now have teams of engineers trying to figure out what sounds their cars should make and they have brought in music composers to help create the sounds.

Automakers have enlisted musicians and composers to assist in crafting pleasing and proprietary alert systems, as well as in-cabin chimes and tones. Hans Zimmer, the film composer, was involved in scoring branded sounds for BMW’s Vision M Next car. The Volkswagen ID.3’s sound was created by Leslie Mándoki, a German-Hungarian prog-rock/jazz-adjacent producer. The Atlanta-based electronic musician Richard Devine was brought in to help in making the Jaguar I-Pace’s voltaic purr. Some automakers cooked up sounds entirely in-house. The Porsche Taycan Turbo S has one of the boldest alerts: you’re in Dr. Frankenstein’s lab as he flips the switch to animate the monster. Engineers in the Audi Sound Lab made the lower frequencies of the Audi E-Tron GT Quattro’s alert by algorithmically mixing different tones produced by recording an electric fan through a long metal pipe; the full alert references the sumptuous soundscapes of the film “Tron” and its sequel.

Other alerts tilt more toward nature. Danni Venne, the head designer behind the Nissan Leaf’s Canto sound palette, said in a Business Insider video that “you really have to go for instruments that don’t have a hard attack to them. Wind instruments, flutes, oboes, clarinets . . . can kind of waver a bit.”

They also try to match the sound the car makes with the ‘personality’ of the car, or rather the personality of the driver who would buy such a car. The person who buys a 9,000 lb Hummer clearly wants to make a different statement from the person who buys a Nissan Leaf, and the engineers try to cater to that.

When the researchers first began working with Renault, Misdariis told me, the collaborators struggled to find a common language in which to talk about acoustic design. “When a graphic designer says to you, ‘This is a red triangle,’ there is no different interpretation possible,” he said. “But if you say, ‘I would like a warm sound’—what is a warm sound? What is a round sound? What is a rough sound? A green sound? What is a smiling sound? We know what happy music is, but what is a two-second sound that is happy?”
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Ford’s Brian Schabel, a sound engineer who, like Moore at G.M., has spent his career in Noise and Vibration, was part of the group that worked on the Mustang Mach E, Ford’s sporty but practical electric S.U.V. “We knew we wanted to keep some aspect of that low-frequency modulation and link it to the past,” he told me. “And then we looked at everything out there. Machinery—what do people associate powerful electric motors with? Formula E vehicles are very high-pitched, raw-sounding. How can we blend those two pieces together? We didn’t want something that was too ‘Batman’ or ‘Blade Runner.’ ” Mach E’s forward sound put me in mind of a hovering dragonfly. The back-up sound is like a broadband cricket.

Seabrook says that our brains get habituated to sounds that we hear regularly and can shut them out, which enables us to live and sleep in noisy places without getting distracted too much. Novelty in car sounds is more likely to alert pedestrians and cyclists than familair background sounds so cars designers are making their car sounds distinctive. But too much novelty carries its own risks .

I asked Moore about the possibility that, by allowing for a unique identity for each of the sixty major auto brands in the world, we were setting ourselves up for a sonic catastrophe—a cacophony of competing thrums and whirs and chimes and tones. If every car is emitting a unique branded alert as it passes under my bedroom window, aren’t my novelty detectors going to go haywire? I described my street to Moore, noting that there is a traffic light about twenty yards away, where there are often six or eight cars waiting. Once the cars are all E.V.s, will I need to move to an apartment at the top of the nearby ninety-three-story Brooklyn Tower just to get some sleep?

Moore replied, “I think with intentional-design thinking we can actually, maybe, make the world quieter. That’s my goal.” However, he added, “we could wake up in five years with eighty per cent E.V.s, and it’s a cacophony of sound and dissonance if these cars are all singing different tunes, in different key signatures and pitches.” Moore speculated that cities might one day have to designate a particular key for all the alerts made in their streets.
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Another possibility is that New York City is just too loud for the relatively civilized decibel levels established for the alert systems by N.H.T.S.A. regulations. Douglas Moore told me that “the levels are set to where a normal person would be able to hear it in a normal situation. It is not expected to be heard in all places”—such as construction zones—“at all times. Otherwise, you’re in the death spiral of just cranking the levels up.”

I recall the first time I heard that beeping sound that some vans and trucks made when they are backing up. It was very effective as a warning and still works.