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Teaching silent hybrid cars to sing

Some people worry that electric vehicles are just too quiet for safety. So why not give them a voice?
/ Source: Forbes

Four years ago, Brook Reeder was an aspiring musician, "sort of doing the singer-songwriter thing" in New Jersey bars and nightclubs. His band never took off and he moved to Northern California to study sound engineering.

Reeder still composes. Only now, instead of playing his music through a Fender guitar amplifier, his sounds purr from behind the fender of a Toyota Prius or, more specifically, from custom-made speakers installed in the car's wheel wells. The hybrid car produces the sound — a cross between the deep putt-putt of the internal combustion engine and the hum of the Jetson's space car — whenever it's moving at slow speeds and would otherwise be silent.

"We can make it sound like anything we want," says Reeder, who is now the lead audio engineer for Enhanced Vehicle Acoustics, a start-up in Santa Clara, which is designing a sound-system package, complete with small speakers, to give an otherwise quiet hybrid a voice. EVA calls its system the Pedestrian Awareness Noise-Emitting Device and Application, or PANDA.

The company was started last year by two of Reeder's classmates at Stanford University with seed money from the National Federation of the Blind. Advocates for the blind have found themselves in the awkward position of protesting the much-loved and ever-growing fleet of hybrid and electric vehicles because they're simply too quiet.

No one has yet been killed by a silent Prius, but anecdotes of close calls abound. In a study conducted by the University of California, Riverside, people could hear a gas-powered Honda Accord moving at 5 miles per hour about three seconds before it reached them. By contrast, by the time they heard an oncoming Prius, it had just passed them by.

One man's threat is another's market opening. "There's a real cool opportunity here for car companies to attach a specific sound to their car for audio branding," says Reeder. "It's a great marketing idea."

Only Harley Davidson has tried to capitalize on a vehicle's sound. In 1994, the biker company tried to trademark the distinctive "potato-potato" roar from a Harley's exhaust pipe, claiming the sound is the result of its bikes' uniquely designed V-twin engine. Harley Davidson withdrew the application years later after other bike makers argued their engines sounded much the same.

The purr of the PANDA Prius, by contrast, has nothing to do with the engine itself. It is, instead, a handcrafted mix of digital recordings — an idling combustion engine, a low-pitched flute, a chanting male choir and other ambient noises.

EVA isn't the only company teaching hybrids to sing. In early August, British luxury sports car maker, Lotus Engineering, debuted its own audio system and sound for the Prius. Lotus isn't interested in gentle chimes: It gives the Prius a guttural "vroom," inspired more by a Porsche than by the Jetsons.

EVA integrates PANDA into the electronics of a hybrid: That means it can take a sound file and then morph that data to match the action of the car. When a car speeds up, the sound file gets compressed and changes pitch; when it slows down, the sound is drawn out.

In principle, PANDA can adapt any sound file. That makes the prospect of car owners downloading a unique ringtone, or "car-tone" to the PANDA in their vehicles a "fantastical, but certainly possible" scenario, says EVA co-founder Everett Meyer.

"Hopefully it doesn't translate into cacophony," says Meyer. His chief concern is how to best alert pedestrians to oncoming traffic. But designing the urban soundscapes of the near future is a tantalizing opportunity, he says. "It's like the Wild West."

Faux engine noise doesn't please everyone. "I don't necessarily think that's the solution," says Catherine Scrimgeour, a spokesperson for ZENN Motor Company, which makes low-speed plug-in cars. "ZENN" stands for "Zero Emission, No Noise." Scrimgeour says ZENN doesn't intend to change its name but insists the company is exploring even more far-out ways to alert pedestrians to its presence.

The Alliance of Automobile Manufacturers, which represents 10 major automakers, including Toyota, says it's waiting to hear the results of a safety study on hybrid and plug-in cars underway by the National Highway Transportation Safety Administration. Ten states and the U.S. Congress are considering so-called Quiet Car bills to study whether there should be rules about a minimum sound level for all vehicles.

Meyer says EVA is talking to a number of potential partners and is also testing a PANDA kit that could be installed in existing vehicles. It aims to begin offering such kits at dealerships by the end of the year. Meyer estimates it will cost car owners about $350 to add PANDA sound to hybrid or electric cars.