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What should a 9,000 pound electric vehicle sound like?

What should a 9,000 pound electric vehicle sound like?

IRCAMRenault’s sounds were indeed surprisingly soft, though perhaps less like a birdsong than a washing machine on the gentle cycle. The Parisian soundscape will certainly benefit from it. But would anyone hear this one? elegance French warnings in New York, especially about the buzz and din of all the gas-powered vehicles on the traffic-calmed streets?

A car powered by internal combustion makes noise. The induction of air, its compression in the piston sleeves, the explosion of the vaporized petrol and the expulsion of CO2 exhaust (“suck, squeeze, pop and blow”, in car talk) produce loud, low-frequency reports, rumbles and vibrations.

At General Motors, the engineers at the Noise and Vibration Center are responsible for fine-tuning that noise. Douglas Moore, a senior expert in outdoor sound at GM, joined the company in 1984, while still a student at Michigan State. He spent nearly eight years of his career at GM, where his job, and that of his noise and vibration colleagues, was to dampen, dampen and modulate internal combustion sounds, depending on the brand. Traditionally, when tuning a Cadillac, Moore and his colleagues tried to make the engine as quiet as possible, because quiet means luxury to the classic Cadillac buyer. In contrast, when tuning a Corvette, Chevrolet’s muscle car, the engineers want to take part of the bang bang bang of internal combustion, because that brings power to the driver.

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

When designing electric versions of popular brands, US automakers must decide whether to mimic the EVs on their gas-powered counterparts or, like Renault, to deviate from the familiar sound. The guidelines of the Passenger Safety Enhancement Act allow automakers to create their own brand warnings, as long as they meet certain specifications.

Moore’s first EV project was the 2012 Chevy Volt, which sent out a pedestrian warning years before the law required it — a vacuum cleaner-like buzz that increased in frequency as the car accelerated. “I have new colors to paint with,” Moore said. “Instead of a palette of internal combustion sounds, I have a palette of AVAS sounds. But it’s the same approach. Instead of generating them with the physical components of the car, which has its pros and cons, we now generate them electronically.”

Moore is also the longtime chair of a group within the Society of Automotive Engineers called the Light Vehicle Exterior Sound Level Standards Committee that helps develop tests that regulators use to measure road safety in the US. His group led research into developing minimum noise standards for EVs and hybrids, and establishing parameters for decibel level, pitch and morphology of the warning signals. Moore once came to NFB headquarters and tried to navigate traffic blindfolded. His NFB instructor was impressed that the engineer could identify a 2005 Chevrolet Camaro and a 2009 Cadillac Escalade by their distinctive engine sounds.

Moore explained the SAE’s relationship with federal highway officials by saying, “We’re figuring out how to measure things. NHTSA says how much.” I asked Moore why the regulations don’t require EVs to be more like ICE vehicles since, as John Paré of the NFB had pointed out to me, we’re already used to those sounds. Moore replied, “The purpose of this sound is to provide information about what the vehicle is doing. And there’s more than one way to do that.” He paused. “Yeah, we’ve learned internal combustion sounds over a hundred years,” he continued. “But before there were any cars around, we knew the clatter of horses meant the wagon was coming. So there’s nothing inherent in those engine noises.”

“But I’m one of the cool ones!”

Cartoon by Suerynn Lee

A well-designed warning reaches the people who need to hear it, without annoying those who don’t. To thread this sonic needle, engineers can vary the decibel level of a particular sound, which indicates the volume of air pressure that the sound waves move, and they can also adjust the pitch or frequency of the sound. Both the decibel level and the pitch determine the penetrance of that sound. The danger is that you create a sound that howls, as it were: it works in the beginning, but after a while it cuts off, so you have to pump the volume up.

Although humans can hear frequencies between twenty and twenty thousand hertz, we hear in “octave bands,” in which the highest frequency is double the lowest. (In a musical C octave, the high C is twice the frequency of the low C.) The regulations specify that: AVAS sounds must occupy four separate, non-adjacent octave bands. A so-called broadband noise of this type, such as the static screeching Amazon vans recently began making when reversing, is less penetrating, more robust, and easier for the hearer to pinpoint than a warning that spans a narrow frequency range, such as the back-up sound. up beepers on Con Ed trucks. Not by the way, the rule of the non-adjacent octave band forbids using any musical phrase as a warning — changing pitch would sound awful — as well as all vocal warnings, human or animal. How would blind people see the street from the sidewalk if electric cars spoke or barked?

By giving automakers the freedom to mark their warnings, the NHTSA rules have created a new design form: acoustic car styling. Pedestrians and cyclists don’t just hear the vehicle approaching; then they know what kind of car it is. For acoustic designers, both EV’s pedestrian warnings and their rich in-cab sound information menus represent the dawn of a new era. “I feel privileged to be working on features that will affect how the world will sound,” General Motors creative sound director Jigar Kapadia told me.

Kapadia, who has a degree in electronics and telecommunications engineering from the University of Mumbai and a master’s degree in music technology from NYU, works with Moore and others at GM’s sound lab in Milford, Michigan. For each sound, the team comes up with some 200 variations and then tests them on their peers in the jury room, until they arrive at some finalists to test on vehicles on the road.

Kapadia likens the sound of an alarm system to a perfume. “Like a perfume, it unfolds,” he told me. “The warning has a base note, a middle note, and a top note.” He added: “These layers are put together to bring out a cohesive organic sound or a futuristic sound, based on the kind of brand we target.” He noted that the pedestrian alarm on the 2023 Cadillac Lyriq, the first electric version of GM’s long-standing luxury car, was made with a didgeridoo, an ancient Australian wind instrument based on the musical interval known as a perfect fifth. But for GM’s nine-thousand-pound electric Hummer, which recently went on sale, Kapadia said, “We wanted a more distorted sound.” He paused, then added, “A bold Hummer sound.” The Hummer’s forward move warning reminded me of the church as the organist begins the next hymn. The background noise is something like its dystopian twin.

To find out what car buyers thought electric vehicles should sound like, engineers and consultants at the Ford Motor Company held “customer clinics” and launched a Facebook campaign. Judging by the response rate, Ford fans were eager to voice their opinion. My own research, based largely on reading comments under YouTube videos of various branded EV sounds, is that most people think EVs not resemble ICE cars. Higher frequencies are believed to denote clean energy and software-driven intelligence; EVs should zoom and zoom like the flying personal vehicles of sci-fi movies like “The Fifth Element,” “Gattaca,” “Blade Runner,” and of course, “Star Wars.” In many cases, Foley artists created the sound effects of these futuristic vehicles based on recorded ICE sound. In Ridley Scott’s “Blade Runner 2049,” the twist is that Ryan Gosling’s flying vehicle sounds like a broken ICE jalopy.