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by yc-kraln
1157 days ago
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Really sorry to hear that. When I worked for Daimler, I was surprised to learn that all of their cars ship with something called "PRE-SAFE Sound" which, when it detects that you might be in a crash (i.e. at the point when the seatbelts are pre-tensioned), it plays a loud-ish burst of white noise through all the speakers, triggering your ears' automatic response which disconnects your ear drums. This means that when the actual (very loud!) crash happens, your hearing is saved. They developed this in the 90s when, after the advent of airbags, they saw that most injuries from moderate car crashes were hearing related. (Here's a video with some cool detail: https://www.youtube.com/watch?v=vTmLYY-Z2rc) I always thought it was a huge shame that 1) this technology isn't required/mandated for all cars and 2) Mercedes doesn't advertise this more |
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The loud part is not the crash itself, but the airbag deployment; it's as loud as a rifle shot because, fundamentally, it is a rifle shot. That's bad in open air; it's way worse in a confined space where that pressure is going to persist for a much longer period of time.
The combustion gas needs to fill the airbag coincident with your face being mashed into it at high speed, and mechanical suppressors slow down the gas so that won't work; using the acoustic reflex (as Daimler clearly does) to get that extra 15 dB of protection means the difference between maximum safe exposure and permanent damage.
I'm surprised that this sound doesn't start playing right before the similarly-explosive pretensioners are fired, since they're also pretty loud, but perhaps they figure it's part of the way to prompt the reflex.