ANR's and hearing loss

[wyoflyer]

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?

[jcoloccia]

Originally Posted by wyoflyer

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?

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.

[jhallrv4]

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

[jhallrv4]

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

[zilik]

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

[jhallrv4]

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

[jhallrv4]

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.

[jcoloccia]

Originally Posted by jhallrv4

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.

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.

[jhallrv4]

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

[jhallrv4]

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