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ANR's and hearing loss

wyoflyer

wyoflyer

Active Member
My son, who flies helicopters for the Coast Guard, called me last night night and told me that they "immediately" told them they would not be allowed to use their ANR headsets. They said a study was done and that it showed ANR's caused irreversible hearing damage. I find this hard to believe, but he was adament about it. Told me I should stop using my Lightspeeds, (which I love). Anybody else hear anything about this?
 
wyoflyer said:
My son, who flies helicopters for the Coast Guard, called me last night night and told me that they "immediately" told them they would not be allowed to use their ANR headsets. They said a study was done and that it showed ANR's caused irreversible hearing damage. I find this hard to believe, but he was adament about it. Told me I should stop using my Lightspeeds, (which I love). Anybody else hear anything about this?
Click to expand...

The thing that really kills hearing more than anything is low frequency thumping. That'll wipe stuff out across the whole frequency spectrum. Possibly ANR is not yet effective against the low frequency thump of the rotor blades. In general, though, I can't imagine what possible ill effect ANR could have. Get more info from your son as something is just not quite right.
 
Being stationed at CGAS San Francisco for a year and a half is what caused my irreversible hearing loss!

I'm thinking about what an ANR headset does...

This is how ANR was explained to me...
First, there is the passive blockage of noise. Then the mic inside the headset samples the noise inside the headset earcups, and feeds it back into the speaker 180 degrees out of phase, effectively cancelling it out. There is considerably less noice in the earcup now, as evidenced by the fact that when I just upgraded to the Bose X from Lightspeed (greater noise reduction)I can now hear things in flight in my NOISY RV4 that I couldn't before; i.e. rattles, etc. that were drowned out by the engine and prop noise.

Also the fact that when the battery fails, or when I use a non ANR headset, I have to turn the radio up much higher than with ANR.

Now, I'm not an acoustic engineer, I don't even play one on TV. But I know what's noisy, and what's quiet. And I was in the Coast Guard. You'll want to keep the BS shields up when they tell you what's good for you.

Jeff
 
low freq thumping...

Good point, I wonder if the C130 and other jet pilots in the guard got the same restriction.
The thumping wasn't so bad in the helos, that mostly happens at the outer portion of the blade, the crew is closer to the center of the disk. Now, the turbine(s) just over your head can be a distraction!

Come to think of it, the exhaust pulses pounding on the bottom of my RV fuselage is more of a low freq thumping. Less than 2700 rpm is hardly high frequency.

Nobody's taking my Bose!

Jeff
 
An audiologist told me that ANR could damage hearing. Not specifically the ANR but the lack of passive noise reduction in most ANR headsets. While ANR reduces the low frequencies well the highs must be attenuated by the passive portion of the headset. High frequencies are just as bad as low when it comes to hearing loss. Bose has almost zero passive noise reduction. She told me to stay away from them. I went with Peltor since they had the highest passive reduction and also ANR for those nasty lows.


Gary
 
Lightspeed sez...

Here's what Lightspeed has to say on the issue, http://www.anrheadsets.com/tutorial101-3.asp
that they say ANR is directed toward low freq noise, as in airplanes, and that the passive reduction is reduced to help effect the Active reduction.

That would mean, I would think, that the passive reduction would allow MORE high freq (turbine) noise through... bad for USCG helo drivers. It would sound quieter to the crew, but the screaming turbine could be damaging even though it seemed quieter.

I'm going to try to get an answer on this from Lightspeed. I know Bose sells helicopter headsets, but don't know if their for turbines.

Jeff
 
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Keep the lightspeed...

Okay, I talked to Joe at Lightspeed, he basically confirmed that a higher "passive" reduction headset would be more effective at reducing high freq noise, he may jump in here himself.

The USCG issue with turbine helos has no bearing on our GA flying in Lycosaurus powered prop planes. Our ANR headsets are tuned for the reduction in the frequencies we are commonly subjected to.

Keeping the Bose, (hey, it was a gift!) and getting a new Lightspeed!! My old trusty Lightspeed is so old, it's made of wood.
 
jhallrv4 said:
Okay, I talked to Joe at Lightspeed, he basically confirmed that a higher "passive" reduction headset would be more effective at reducing high freq noise, he may jump in here himself.

The USCG issue with turbine helos has no bearing on our GA flying in Lycosaurus powered prop planes. Our ANR headsets are tuned for the reduction in the frequencies we are commonly subjected to.

Keeping the Bose, (hey, it was a gift!) and getting a new Lightspeed!! My old trusty Lightspeed is so old, it's made of wood.
Click to expand...

This does make sense. Normally there's nothing you'd really consider high frequency in a GA cockpit....at least nothing of consequence that even the crappiest headsets couldn't effectively attentuate. Turbines hadn't even occured to me. Yes, it makes absolutely perfect sense that ANR may very well be worse for a turbine environment like a helicopter than a quality passive set.
 
Excellent point, Gary. Isn't anyone in Colorado working this morning?

I don't think we really have that much of a high frequency problem in the RV's. The wind whistling past and through the airframe is probably about it.

I've turned the active NR off in all three of my ANR headsets, a Bose, Lightspeed (old 20 model) and Headsets, Inc. modified David Clark, (really old) and they all have a fair amount of passive reduction, the worst being the modified DC.

With the ANR off, in flight at around 170kts, there is still a significant amount of additional noise when the earcups are pulled away from the ears.

HOWEVER, when I converted the DC's to ANR, the passive reduction was considerably reduced. When the battery failed in the Lightspeed, there was much better passive reduction remaining. I think the Bose is somewhere in between. These were on different flights, so hard to tell for sure. If you really want some serious passive reduction, check out the Lightspeed QFR series. They post some impressive numbers. Peltors are comfy too, as I recall.

Jeff
 
Back in the 70's (the 1970's, yes) we wore earplugs, AND headsets (built into the brain-bucket, when we flew in helos. Very effective, but not that comfortable. That was ANR, as you actively put the plugs in your ears.

Jeff
 
Earplugs

They had earplugs in the 70's? When I learned to fly in the 70's, we were real he men - no earplugs, just a lot of yelling and ringing in the ears. Hmmm, that ringing is still there....
 
jhallrv4 said:
Good point, I wonder if the C130 and other jet pilots in the guard got the same restriction.
Click to expand...
I'm not CG, but the AF is starting to issue us ANR headsets... so I guess the panic hasn't reached across service lines yet.
 
Anr

The active nois reduction is a factor of MORE noise being generated inside the ear cup---------think about it, the only way this can work is there is DOUBLE the sound occouring in the ear cup.

The real question, IMHO, is -------do the out of phase signals actually cancel out the existing noise (pressure waves), so that there is nothing left to reach your eardrum, or is it that both sounds reach your eardrum, and your poor brain hears BOTH, and just cant process the info, so you hear "nothing".

You dont have to "hear" noise for it to affect your hearing.

Anyone out there who isnt an employee of a headset company, who is knowledged in this area care to render and un-biased opinion????

Just for the record, I fly with old David Clarks modified with Headset Inc. kits--------LOVE them.

Mike Starkey
-10
 
If a tree falls in the forest......and Yogi is wearing ANR headsets that he stole from the Ranger......does Yogi........Oh never mind.

I think the active NR cancels the noise wave so it's eliminated. Your ear doesn't hear it because it's not there.

I think this discussion is pretty funny though. Go fly an RV without headsets for an hour. You'll have all the answers you need. I can't imagine my hearing would be better off without ANR or without headsets, but I guess stranger things are possible.
 
Tones

Is anyone using aural warning tones for the electric trim motors? How about altitude alerting & overspeed? Stall warning? Autopilot disconnect?

If so, are the tones being fed into the audio system to play into the headsets? How about out of the headsets for the times you might not be using them?

Our Part 25 corporate jet uses sonalert "C" chord altitude alert, a pitch trim clacker, and others that don't feed into the audio control. Individual care must be taken so that passive and active noise reduction don't prevent hearing these tones.
 
Mike S said:
The active nois reduction is a factor of MORE noise being generated inside the ear cup---------think about it, the only way this can work is there is DOUBLE the sound occouring in the ear cup.

The real question, IMHO, is -------do the out of phase signals actually cancel out the existing noise (pressure waves), so that there is nothing left to reach your eardrum, or is it that both sounds reach your eardrum, and your poor brain hears BOTH, and just cant process the info, so you hear "nothing".

You dont have to "hear" noise for it to affect your hearing.

Anyone out there who isnt an employee of a headset company, who is knowledged in this area care to render and un-biased opinion????

Just for the record, I fly with old David Clarks modified with Headset Inc. kits--------LOVE them.

Mike Starkey
-10
Click to expand...

I'm not an employee and I'm knowledgable about this :) It really does decrease the pressure levels. The kind of wave being produced really is irrelavant, but it's easier to imagine if you think of sound waves as they really are...longitudinal waves, i.e. they pump back and forth as if you where holding a slinky and pumped your arms towards each other. The wave travels like that, not transverse motion like moving the end of a rope and making little sine waves.

So if you think of a person standing up, he can squat up and down in a sort of pistoning action. That's like the sound wave. The ANR is as if he's standing on a platform. When we squats down, the platform goes up. When he goes up, the platform squats down. End result is that if he's holding something (surrounding air molecules, for example) there is no energy transfered since he's doing no work. All the energy of him going up and down and the platform moving all around is dissipated as heat.

Some of the early ANR stuff that I experimented with back in college DID, in fact, introduce very irritating artifacts into the mix. There was often loud hissing or a low frequency rumble that just drove you batty. This was just because the technology available to a peon like me was immature. Now, even crappy ANR does a reasonably good job.

edit: don't everyone send me 30 bazzilion e-mails about work and thermodynamics and blah blah blah....it's close enough for this :p
 
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Thanks!!!

John, thanks for the answer.

I knew the cancelation was from out of phase waves, just didnt know if the actual effect took place prior to our hearing it, or just mental reaction to conflicting info recieved by the brain.

Sound pressure is really the question here, glad to hear your answer.

Mike
 
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Hearing loss from exposure to sound is caused by mechanical damage to our hearing apparatus from the absolute magnitude of sound energy we are exposed to over time.

High frequency receptors are the most susceptible to damage and indeed those of us over 40 (most of us based on the pictures I have seen :D ) already suffer from significant age related high frequency (presbycusis) hearing loss.

Not to worry those of you under 40 will catch up to us one day :rolleyes: . The younger generation will get there quicker if they do not turn down the volume on that garbage they call music. (garbage meaning anything post Beach Boys :cool: )

In any event it is the total magnitude of energy delivered by all frequencies delivered to the auditory canal that correlates with the degree of hearing loss compounded by total time of exposure.

From the standpoint of the physics and biology involved it makes sense that ANR headsets reduce the total magnitude and therefore over time would decrease hearing loss and not increase it.

I too learned to wear earplugs under my headset in th 60s in helicopters and C130s. (who said you can't teach a jarhead new tricks) I still wear a pair of shooters plugs under my lightspeeds and feel this combination offers the best overall protection. Flying a Rocket or RV to me is unbearable without ANR.

Why the Coast Guard would make such an edict is beyond me. It makes no biologic or physiologic sense. ANR has not been around long enough or in wide enough use to have made any clinically significant meaningful studies to come to any conclusions that would support their decision.

http://engineering.dartmouth.edu/thayer/research/noisereduce.html

http://mywebpages.comcast.net/rmnelson2/index.html

http://cf.alpa.org/national/departments/eas/comms/hft/anr-reportprject.htm

http://www.avweb.com/news/avionics/183226-1.html
 
From:

http://www.e-a-r.com/pdf/hearingcons/anr.pdf

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This paper is actually pretty interesting. If I understand correctly, the conclusion is that ANR earmuffs don't typically provide as much passive protection due to the way they must be constructed, so at frequencies where the ANR is not effective, you are receiving more noise than you would with a conventional earmuff.

PJ
 
jcoloccia said:
This does make sense. Normally there's nothing you'd really consider high frequency in a GA cockpit....at least nothing of consequence that even the crappiest headsets couldn't effectively attentuate. Turbines hadn't even occured to me. Yes, it makes absolutely perfect sense that ANR may very well be worse for a turbine environment like a helicopter than a quality passive set.
Click to expand...

I am sure there is a lot of high frequency in the 'White Noise' in an RV cockpit, it's just not apparent as it is mixed in with all the other frequencies.
Pete.
 
It always helps to ask an "expert"

Turns out I have one in the family. One of my older brothers is an EE and used to be the head stereo designer for Audio Research.

After reading this thread, here is what he had to say:
a couple of comments.
First I am speculating here,

1. Your ear has some amount of gain control, that is, it has feedback which tries to reduce high noise levels or it tries to amplify low noise levels. In the plane it will be doing the first. Cutting your ears gain.

2. This feedback may be more sensitive in the 1K area where the ANR headsets reduce the most. I don't know this but it makes a lot of sense as your ear is most sensitive here.

3. Thus your ear is "wide open" to the high frequency noise making the ear more susceptible to damage.

I would go with the best passive which also has ANR.
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Simple, good advice.
 
I remeber, that during the time I learnd to fly, twice a week half a day, with an DC ANR, over a half year period, that I have to screw up the television and radio at home one or two digits higher to understand what they are talking about!

This disapeared after the flying lessons where finished and I only flew a few hours a month.

I think that with an ANR, you do not recognize the noise, but the ear gets treatet with a high level of noise.

just my feelings, but I'm still using my ANR and love it.

Dominik
 
I wear my molded earplugs with my Flightcom ANR Classic. I also wore them with my DC 13.4s before I got my ANR. I am also VERY paranoid about my hearing as I need my ears to do my job. (Sound engineer, Entertainment industry) I personally would like to see a set of affordable high rejection in-ear monitors to wear for the audio. Of course you would also need some type of really lightweight headset. If these things can hold up well in a 120+dB onstage environment then they should be great in the cockpit. (The music will sound great too!)


Jeff
 
Interesting

Coast Guard issue I am not sure of but in the airlines it is required that the headset must be TSO'ed. The cockpit of a jet is fairly quite, but I do know a fellow pilot got a set of expensive TSO'ed Sennheiser headsets. He said at the end of the day he was less fatigue. I will admit the Sennheisers are not BIG cups like a DC or Lightspeed, so their passive is not great but they don't need to be, considering we are using single ear pieces or small Telex Walkman style looking things. The Senn's are way more substantial in all respects to "jet" headsets and the ANR does work.

You can't use Lightspeed in airlines because they not TSO'ed and we have to talk to the other pilot. So full coverage (BIG CUP HEAD SETS) are NOT really cool for two crew operations unless you pull one ear cup off the ear, which defeats the purpose. Believe it or not most airlines do not have full time VOX intercoms.

I don't know if the military thing is a TSO or Mil-spec approved equipment type thing. It may be worry of compatibility. Helicopters and some military intercoms use different impedance than civilian gear. The reason that was given, hearing loss sounds suspect from common sense to me, but I am not an audio expert.

As far as injection molded and "little" jet type headsets for RV's I think that is a joke for RV's.I disagree ANR's all lack passive noise suppression, but the "Jet" style ANRs, like the Sennheiser's and in the ear units are NOT suitable in my opinion.

The passive protection from GA D/C style headsets comes from the seal and clamp pressure, which is function of hearing protection. The big cups if you will dampen your skull from vibrating in essence.

Most Sear's stores have a hearing aid department and can cast a wax impression and make a custom mold of the inner ear. I have two and they work with my "jet" Telex, but I would never consider anything like this for my RV, even if a plug was in both ears. The big cups that go around the whole ear and part of the skull is what (passively) dampens noise.

As far as ANR I can't see a down side except expense and batteries, but I guess seeing is not the issue, hearing is, hahahaha. :rolleyes: (bad I know)

George
 
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jumping in late on this....

But for what it's worth, my NASA flight surgeons bug me at every physical to make sure that I am wearing good a good ANR headset AND earplugs under that for all my personal flying. (They weren't pleased that my helmet didn't have ANR, and we're getting that added.) They just can't reverse that loss from all my early years flying J-3's and the like without headsets or ear plugs...and want to keep me from losing any more!


Paul
 
In ear style

A while back I asked if anyone was using the Clarity Aloft, in ear style headsets. Several were and really liked them.

I will be buying very shortly and am leaning toward these. I wonder how these play into this discussion.

Darwin N. Barrie
Chandler AZ
 
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