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Mercedes's Pink Noise Says: Prepare For Impact

The new Mercedes-Benz E Class braces your eardrum against the potentially deafening noise of a crash

2 min read
New tech predicts crashes and produces noise that protects your hearing.
Illustration: Mercedes-Benz

Dumb cars shield against crashes. Smart cars avoid them. Shrewd cars prepare you for them.

This year, Mercedes-Benz is introducing what surely is one of the shrewdest precrash features yet: a burst of sound that causes a muscle inside the ear to contract, bracing the eardrum against the potentially deafening noise of the crash itself.

Tip o’ the hat goes to IEEE Spectrum’s auto maven, Lawrence Ulrich, who pointed out to us the importance of “Pre-Safe Sound,” standard in the 2017 E class.  (Ulrich will describe this and other marvels in “Top Ten Tech Cars,” in our April issue.)

The idea of pre-crash safety has been out there for a while. For instance, a car can instantly tighten the seatbelt to minimize movement and prevent the body from “submarining” forward, under the belt. Or it can inflate a tiny airbag to nudge the driver toward the center, protecting against side impact. Or it can close the sunroof, adding to the rigidity of the cabin.

But Pre-Safe Sound goes to ear-popping lengths. When the car’s sensors sense an impending crash, the cabin is filled with a burst of “pink” noise, a broad spectrum of frequencies in which the power is inversely proportional to the frequency. That triggers the so-called acoustic reflex, in which the stapedius muscle—the smallest muscle in the body (remember that for Trivial Pursuit)—contracts, bracing it, the bones of the inner ear, and the eardrum.

The pink noise is around 80 decibels, about equal to that of a dishwasher and completely safe. A crashing car puts out around 145 dB, high enough to damage hearing, at least some of the time. Worse still—and this part is not emphasized by Mercedes-Benz or any other carmaker—is the noise created by the near-instantaneous deployment of the airbag: around 165 dB. It’s estimated that 17 percent of the people who are exposed to airbag deployment suffer some degree of permanent hearing loss.  

That’s why its important to put the various safety features into action in the right order. First comes totally safe features, like emergency braking, seltbelt pretensioning and Pre-Safe Sound. The airbags come only when necessary, during the crash itself.

Pre-safe noise took a long time to go from a gleam in an inventor’s eye to a commercial offering.  A U.S. patent for the idea was filed in 1997 by one Armin Kausch, an employee of a subsidiary of TRW Automotive. That patent application cited earlier work going back as far as 1960.

It takes time to get the bugs out. Remember that whenever you read that cars without steering wheels will be plying our roads before your kids are old enough to get a driver’s licence.
 

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Chinese Joint Venture Will Begin Mass-Producing an Autonomous Electric Car

With the Robo-01, Baidu and Chinese carmaker Geely aim for a fully self-driving car

4 min read
A black car sits against a white backdrop decorated with Chinese writing. The car’s doors are open, like a butterfly’s wings. Two charging stations are on the car’s left; two men stand on the right.

The Robo-01 autonomous electric car shows off its butterfly doors at a reveal to the media in Beijing, in June 2022.

Tingshu Wang/Reuters/Alamy
Purple

In October, a startup called Jidu Automotive, backed by Chinese AI giant Baidu and Chinese carmaker Geely, officially released an autonomous electric car, the Robo-01 Lunar Edition. In 2023, the car will go on sale.

At roughly US $55,000, the Robo-01 Lunar Edition is a limited edition, cobranded with China’s Lunar Exploration Project. It has two lidars, a 5-millimeter-range radar, 12 ultrasonic sensors, and 12 high-definition cameras. It is the first vehicle to offer on-board, AI-assisted voice recognition, with voice response speeds within 700 milliseconds, thanks to the Qualcomm Snapdragon 8295 chip.

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