Actually, if you pick the correct app they are surprisingly accurate: http://scitation.aip.org/content/asa/journal/jasa/135/4/10.1...

Having done sound testing extensively, you can be sure in an airplane positioning and sound source and sound type can drastically impact your measurements. Multiple reflections can re-enforce, or reduce the measured level. The type of sound measured is very important as well.

He's not measuring pink noise on the airplane, what the measured level of a particular sound is, needs to be normalized to really understand what effects it will have on you.

I'm sure in a good test setup the smartphone can get you pretty darned close. I'm more concerned with this guy's test setup than the equipment used.

> for A-weighted sound level measurements three apps had mean differences within ± 2dBA of the reference measurements. For un-weighted sound level measurements three apps had mean differences within the ± 2 dB of the reference measurement. Since national standards and occupational guidelines specify that type 2 sound measurement instruments have an accuracy of ± 2dBA, some of the above-mentioned apps could potentially be used in the occupational setting

http://blogs.cdc.gov/niosh-science-blog/2014/04/09/sound-app...

To put it in numbers: ±3dB is doubling/halving of Power, but humans typically perceive a change of ±10dB as doubling/halving of "Volume". Also the damaging effects of noise typically scale as double-the-power, half-the time.

And personally I'd rather not be in the situation where I'd ponder if the damage to my hearing is double or half what it should be if my iPhone app were accurate: I'd rather have it show numbers that are 20dB below this level, so that I can be assured of no significant damage at all!

Side note: I'm always curious how soldiers/SWAT/HRT/etc. are able to hold normal volume conversations. If they're wearing ear-protection, how do they listen for potential threats and assailants? If not, how do they not shout all day long every day?

The technology would be similar to that used in hearing aids and noise-cancelling headphones. But it is also probably an order of magnitude or two more expensive just because the primary customers are tax-funded.

Without electronics, I could also conceive of an earplug with a winding channel bored through it, past flaps that can block the channel by moving too far in either direction and forming a seal with the outer wall of the channel. Sound energy above a certain level would push the flaps closed as the air vibrated, and would thus attenuate louder sounds to a greater extent than quieter ones. If the flaps were tuned to different sound energies, the loudest sounds would push closed the most flaps.

That would require some precise machining to fit inside the outer ear canal. The electronic filter might actually be cheaper.

If an over-the-ear tech is available for civilians for $70, I would guess that an in-ear police/military version is $850, with an upsell option to integrate with your existing radio communications system for only $1150 per pair. I'd also call it "active hearing protection system" and never, ever refer to them as "earplugs".

That's comparable with a good hearing aid, only because the health insurance payments system is superficially similar to government procurement contracting with respect to profiteering middlemen.

Again, this is only a guess, made without supporting data by someone who owns a foil hat.

http://archive.armytimes.com/article/20090908/NEWS/909080313...

> Soldiers can adjust the rocker with a quick "click" depending on the amount of protection they need. When it's in the open or "weapons fire" position, sound can travel through the sound channel filter into the ear.

> For noisy environments that don't require an acute listening capability, such as around helicopters, troop carriers or generators, the rocker can be switched to the closed or "constant protection" position.

There's also larger over-ear kinds that are integrated with comms:

http://www.bosssafety.com/p-10356-peltor-comtac-iii-a-c-h-he...

This style has both active and passive configurations.

They don't seem to have variable attenuation based on the acoustic energy, though. If the soldiers find them to be acceptable everyday gear at all, there would certainly be funding available to engineer improved internals.

The over-ear comms-integrated rig is priced at double my estimate for what an in-ear version might sell for, which tells me that I was probably underestimating.

You can achieve reasonable short-term protection by holding your hands flat over your ears. It doesn't reduce the subjective volume, but it does [anecdotally] prevent subsequent symptoms that indicate temporary or long-term damage has occurred.

Not flat... that won't do much. They must be cupped... basically you make a letter "C" with your hands then old that up to your ear with your side of your palm (pinky side) resting on your temple.

This will deflect the sound wave around your ear. Old-school artillery trick.

My biggest question is how much training airlines give pilots about exactly what to say on these updates - on a recent flight, the pilot said that a critical system in the plane went from "too broken to take off" to "yep, that looks fine" with a couple of restarts just before we left the gate. I'm sure he did everything per spec, but I'm not sure how helpful it is to tell everyone that they are riding on equipment that's only legal because the turn-it-off-and-on-again principle isn't just for IT.

Yeah, but there's no reason for the people operating the PA to blast our ears for mundane drivel. I was on a flight last weekend where, because I was right next to a speaker, I had to cover my ears for 5 minutes while the flight attendant droned on about non-emergency stuff. It was so loud it hurt my ears. I already have tinnitus, so I don't need any more hearing loss.

The safety talk was at the beginning of the flight and it was much lower in volume than what I'm talking about.

My guess is that the attendant's mouth was too close to the mic and they were just talking way too loud.

Also if you get on a new model plane, things might be different.

The point isn't to not do the presentation, the point is to acknowledge that most people ignoring it don't need it and hence there isn't a need to YELL IT SO LOUD OVER THE PA THAT EVERYONE IS AT RISK OF HEARING DAMAGE.

however, in the absence of anything else it is an indication.

The number it assigns it might as well of been made up... or put on some App-specific scale like 1-10, 10 being "we think this is really loud".