Passenger hearing protection

[Shearwater]

I'm not a pilot, but work offshore so I'm a regular helicopter passenger and have registered on here to see if someone can help with a query.

Before leaving the departure lounge, all passengers fit ear plugs. There are ear defenders provided on the helicopter, but for reasons of comfort, quite a few people opt not to wear them.

We have a manager who insists that ear defenders must be worn on a helicopter, not for noise attenuation, but to reduce the vibration into the skull. He says that the ear plugs can be removed on the aircraft if desired, before putting on the ear defenders.

Despite extensive searching, we are unable to find any evidence to support his theory. On the contrary, we have found numerous sites which say that ear plugs give better attenuation for the frequencies found in the cabin. None of them mention anything to do with reducing vibration to the skull.

Does anybody on here know anything about this theory, or can direct me to a site which can give more information.

Thanks

Donald Hadden

[Tony Chambers]

i'm not a heli pilot either but have been working both on the ground and some crewing with various heli's for 14 years, i have never heard of ear defenders stopping head vibration. The best contact i would presume would be the heli operator who would be able to clarify any such phenomenum.

[simfly]

Hmmm, never heard of ear defenders reducing vibration to the skull..... I'm very interested to know if this can be true, first time i've heard of it.

Donald, one way you could reduce vibration is to change your flights by a week and sit on Janette's lap :E

[heedm]

I think what he should have said is that the ear plugs stop sound going up the ear canal. If the sound hits hard structures nearby (ie skull) they will be transmitted to your inner ear. The ear defenders will reduce this transmission of sound.

The best protection is to use both.

[simfly]

One thing I've noticed flying both helicopters and fixed-wing (piston engined though) is that if I wear ear plugs under my headset, the plugs seem to cancel out most of the engine noise (headset doing it to an extent obviously), but speech over the intercom and radio is almost unaffected. The first time I tried this it amazed me how clear speech was despite the ambient sound being so quiet. I assume, hopefully someone can correct me, that plugs cancel out the louder (higher frequency??) noise but not so good at the quieter (lower frequency??) noise.

[OFBSLF]

I'm agree with Heedm.

The noise reduction rating (NRR) for in-ear plugs is greater than that of over-ear muffs. It is my understanding that some of what we hear comes from the vibration of bone structure surrounding the ear. In-ear plugs do not provide any protection for that frequency spectrum, but muffs do.

When target shooting, I use both in-ear plugs and electronic muffs that limit amplified sound:

http://www.aosafety.com/shooters/products/tac_01.htm

[419]

Shearwater,
One thing no-one has mentioned yet, is the hygiene aspect of using ear defenders.
I work for a large helicopter operator, and I often have to repair (change ear seals etc) pax ear defenders. If I was to describe some of the things I've seen inside, I'm sure you'd never wear them again. ( I now wear disposable gloves whilst repairing them). They do get sprayed with a special disenfectant occasionally, but this does nothing to clean the crud from the insides.
If you fly a lot, I would recommend either buying your own ear defenders, of always carry a small pack of disinfectant wipes. (the ones for telephones are ideal)

All helo pilots should also take note of this, and change the ear pads and internal foam of your headsets on a regular basis. These tend to only be replaced when the headset is being repaired. some of the stuff I've seen inside these would make very good biological weapons!, and they are sitting on your ears for hours on end.

419

[2Sticks]

Does anyone know whether there are any risks associated with using the newer style headsets with electronic noise attenuation systems. I've tried them as a passenger so I know how effective they are, but not as pilot. Could they prevent you hearing noises that should be alerting you to problems with the helicopter's systems?

2Sticks :confused:

[MPT]

G'day 2Sticks,

I've been using earplugs and a Gallet helmet (helmets also help to minimise the transmittance of the sound through your skull) with ANR and I've found that any "out of the ordinary" type sound is easier to hear. The radio is also a lot clearer than without the noise cancelling.

Cheers,

MPT

[Droopy]

Don't most modern sets incorporate earphones to facilitate PA announcements, which would be at just as necessary as extra hearing protection?

[4ero]

IIRC your skull and jaw transmit around 40db to your ear drums even with protection. A helmet would reduce it by protecting your head from the sound waves, but i don't think muffs would.

Maybe if you have them really really tight your skull won't act like a sound board. :)

[Blind]

Shearwater, my advise is steer well clear of the ear defenders. I have never seen them being cleaned and I would be really traumatised if someone made me wear them. I would also bet money on them not doing much in the name of ear defending

Eugh:yuk: