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Comment by pja | Hacker News Reader

It’s not "research research" but it is "does this phenomenon actually exist in the literature" research.

Insisting on testing the phenomenon in an actual car crash seems superfluous to me. A car crash produces a loud noise that can potentially damage hearing, which can be alleviated to some extent by triggering the acoustic reflex with a quieter noise immediately before impact. So long as the generated noise is well below the threshold of damage then I’m really failing to see why more specific research is required in order to believe that this would be an effective intervention.

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Yes, sorry - to be clear, I wasn't questioning the existance of the actual reflex. More the protective effect - however I understand that my post probably wasn't worded very well.

The bit about the noise from a car crash being loud enough to damage hearing after a one-time short exposure is what I doubt. Sure it's loud, but does a split second exposure to it really do permanent damage? I don't know what the answer is, but I am skeptical about the usefulness of this feature.

Well, consider that an air bag is basically a bomb going off in your face. And I'm pretty sure explosions from up close cause at least temporary hearing damage.

> Deployment of a driver’s side front airbag will generate mean peak sound pressure levels of approximately 160 dB (decibels).

> Studies have shown that the pain threshold from noise is about 140 dB and that a single exposure to sound pressure of this level can cause permanent, severe hearing loss.

> The deployment of a side airbag generates a mean peak sound air pressure of 178 dB.

So yeah ... a car crash will definitely mess with your hearing permanently.

[1]http://hearinghealthmatters.org/hearinginternational/2012/th...

Stand by some one at the range without ear pro and ask them to shoot one shot.

The sound is only a fraction of a second but that ringing you'll hear is the death sound of the frequency you'll likely never to be able to hear again.

You also need to understand that sound and loudness isn't what causes hearing loss it's the pressure shockwave.

If a blast "noise" is mostly outside of your hearing range the pressure will still do permanent damage.

When a bomb goes off most of the energy can very well be outside of the normal frequency range of the human ear, it will still however rip your ears apart.

that ringing you'll hear is the death sound of the frequency you'll likely never to be able to hear again

or you'll hear it all the time

Any noise over a given decibel threshold damages hearing.

I think the problem in car crashes is probably the airbags though: airbag inflation is very loud. One article I found ( http://www.sae.org/standardsdev/tsb/cooperative/airbag.htm ) suggests 170dB, vs 140dB for the car crash itself.

170dB is well within the 'can cause permanent hearing loss' range. 140dB is 'this hurts' (and probably causes hearing loss).

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