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Helmet query

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Helmet query

Old 28th Jun 2020, 05:43
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Helmet query

Gents

I am placing an order for an MSA Gallet 250 helmet that is offered with multiple configs, i.e. Bose, Lightspeed, DC, No ANR etc.
Any feedback from the industry ref performance?
I used both Bose and Lightspeed headsets stand-alone in a B412 previously and the Lightspeed blocked out the MR Low RPM horn. It also created feedback if the opposite pilots window was open.
The Bose did not block out the Low NR horn but also created feedback if the opposite pilots window was open.
has anyone experienced this utilizing both configs in a helmet?


Thanks
D
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Old 28th Jun 2020, 11:03
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If you have a good system (either in the helicopter, or in the headset), it should give you the option to modify the sensitivity of the "hot mike"-that should take care of the ambient noise issue.

I personally do not believe in the benefits of an ANR.

To me, passive noise reduction is the way forward.
I have been using custom molded ear plugs from the beginning under my helmets and headsets.

25 years and over 8000 hours later, my hearing is still excellent...
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Old 28th Jun 2020, 14:22
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Originally Posted by hueyracer View Post
I personally do not believe in the benefits of an ANR.

To me, passive noise reduction is the way forward.
I have been using custom molded ear plugs from the beginning under my helmets and headsets.
ANR is not a bad thing. ANR is primarily for folks who don't want to wear muffs and plugs together. It's all part of a continuum of noise reduction options. From least effective to most effective:

1. Passive headset alone (assumes a high quality headset)
2. Earplugs alone (assumes a high quality, well fitted earplug)
3. ANR headset (assumes a high performance brand, i.e. Bose, Lightspeed, DC)
4. Passive headset with earplugs underneath

Not sure about ANR with plugs underneath. Current ANR engineering assumes an open ear canal. Has anyone tried that?

Make no mistake, there are blurry lines between all of those choices. Headsets, both passive and ANR, have better performance at low frequencies, earplugs at higher frequencies. Depending on your current state of hearing loss, the spectral content of the noise, and the psycho-acoustics associated with what types of noise bother you the most, your mileage may vary by quite a bit.

At the end of the day it's a trade off between performance, convenience, comfort and cost. Personally I bounce between options 2 and 3 listed above. On hot days I prefer to err on the side of light weight and thermal comfort (Clarity Aloft) vs. convenience, irritated ear canals, and ultimate noise attenuation (DC ONE-X). But I'm flying without a helmet and flying relatively quiet Robinson products. If I was in noisier territory, or required/desired to wear a helmet, CEPs under helmet muffs would likely be my choice.

Here's an interesting article on how ANR is quite obviously just another layer in the arsenal.





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Old 28th Jun 2020, 15:25
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Originally Posted by aa777888 View Post
ANR is not a bad thing. ANR is primarily for folks who don't want to wear muffs and plugs together. It's all part of a continuum of noise reduction options. From least effective to most effective:

1. Passive headset alone (assumes a high quality headset)
2. Earplugs alone (assumes a high quality, well fitted earplug)
3. ANR headset (assumes a high performance brand, i.e. Bose, Lightspeed, DC)
4. Passive headset with earplugs underneath

Not sure about ANR with plugs underneath. Current ANR engineering assumes an open ear canal. Has anyone tried that?

Make no mistake, there are blurry lines between all of those choices. Headsets, both passive and ANR, have better performance at low frequencies, earplugs at higher frequencies. Depending on your current state of hearing loss, the spectral content of the noise, and the psycho-acoustics associated with what types of noise bother you the most, your mileage may vary by quite a bit.

At the end of the day it's a trade off between performance, convenience, comfort and cost. Personally I bounce between options 2 and 3 listed above. On hot days I prefer to err on the side of light weight and thermal comfort (Clarity Aloft) vs. convenience, irritated ear canals, and ultimate noise attenuation (DC ONE-X). But I'm flying without a helmet and flying relatively quiet Robinson products. If I was in noisier territory, or required/desired to wear a helmet, CEPs under helmet muffs would likely be my choice.

Here's an interesting article on how ANR is quite obviously just another layer in the arsenal.
It also largely depends whether you fly piston or turbines. Max passive noise attenuation is key to filtering out the high pitched turbine noise. ANR is not that effective here. And rumors Are that the anti-noise created by the ANR headset creates long-term damage to the ear.

If you fly piston however, ANR is really good at suppressing the low frequency drone of the piston engine. Passive headsets, and helmets with merely passive noise attenuation won’t get rid of that engine noise.

ANR headsets often don’t work at all with ‘doors open’. I think this is what the OP describes with “copilot window open” etc. The ANR system gets confused by the wind buffeting, and creates an unbearable artefact
noise. I personally had this with the Bose A20. I would assume that this is lesser of a problem when the ANR headset speakers are embedded in a helmet, but can’t speak from experience here.
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Old 28th Jun 2020, 16:31
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Originally Posted by Hot and Hi View Post
It also largely depends whether you fly piston or turbines.
That's what I said, I just said it differently

And rumors Are that the anti-noise created by the ANR headset creates long-term damage to the ear.
This is total nonsense. It's amazing that any pilot, who is supposed to have at least some rudimentary understanding of technical matters, could even begin to believe such junk. If things sound less noisy it is because your eardrum is moving less. If your eardrum moves less then the wear and tear on it is also less. Can you find locations inside the earcup where the aggregate sound level is higher with the ANR on? Of course you can, because the ANR-generated anti-noise does not combine destructively with the noise at those points. But at the eardrum, where the anti-noise combines destructively with the noise, the sound pressure levels and hence the movement of the eardrum (and thus all internal ear structures) is greatly lessened. It's basic, high school (fifth form) physics. Don't you remember the water tray interference pattern experiment?

ANR headsets often don’t work at all with ‘doors open’. I think this is what the OP describes with “copilot window open” etc. The ANR system gets confused by the wind buffeting, and creates an unbearable artefact
noise. I personally had this with the Bose A20. I would assume that this is lesser of a problem when the ANR headset speakers are embedded in a helmet, but can’t speak from experience here.
This is highly variable. I have experienced mild buffeting issues with my DC ONE-X, but only when I stick my head out into the air stream, not something I really need to do. I can't speak to the Bose or Lightspeed, but the DC ONE-X has been vastly superior for me compared to regular, passive David Clarks in both Robinson and Airbus products, doors on or off, open or closed. I even had a chance to run the ONE-X's in a UH-60 for a week (thanks to a cool little mic impedance matching gadget). Again, greatly superior to the military supplied headsets. I will say that the MRGB whine was somewhat fatiguing, however the overall noise level was far more fatiguing than that when using the passive headsets. And the doors were open on that ship all week, too.

Things do get really weird, often unusable even, when you cup or cover the external noise sensing microphone with your hand. Not being a helmet user I wonder how the ANR helmet installations handle the placement of those microphones? That by itself may be the source of some of the reported issues.

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Old 28th Jun 2020, 17:52
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Originally Posted by Hot and Hi View Post
ANR headsets often don’t work at all with ‘doors open’. I think this is what the OP describes with “copilot window open” etc. The ANR system gets confused by the wind buffeting, and creates an unbearable artefact
noise. I personally had this with the Bose A20. I would assume that this is lesser of a problem when the ANR headset speakers are embedded in a helmet, but can’t speak from experience here.
This is exactly what I experienced with both the Bose A20 and the Zulu 2 in the 412 but not in a 206 or 407 with windows open and air scoops fitted.
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Old 28th Jun 2020, 18:29
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Originally Posted by aa777888 View Post
Things do get really weird, often unusable even, when you cup or cover the external noise sensing microphone with your hand. Not being a helmet user I wonder how the ANR helmet installations handle the placement of those microphones? That by itself may be the source of some of the reported issues.
Good question. I’m curious about that too...
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Old 28th Jun 2020, 18:44
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There’s no chance an ANR headset designed to work unobstructed will work, unmodified, within a helmet.
alarm buzzers aren’t usually within a frequency/decibel range that should be sufficiently attenuated to become inaudible.
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Old 28th Jun 2020, 21:08
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Never had a problem hearing the Robinson horn with either Bose or DC ANR. Never had a chance to try the Lightspeed stuff.
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Old 29th Jun 2020, 03:00
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Honestly there’s no substitute for CEP or equivalent when flying 412’s or utility work requiring doors off etc
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Old 29th Jun 2020, 05:48
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Originally Posted by aa777888 View Post
Things do get really weird, often unusable even, when you cup or cover the external noise sensing microphone with your hand. Not being a helmet user I wonder how the ANR helmet installations handle the placement of those microphones? That by itself may be the source of some of the reported issues.
In the original military design for the Mk4A helmet (entered service in 1997), the two low profile transducers in each helmet capsule sat just in front of your earhole about an inch apart, fitted to a printed circuit board.

The design highlighted the need for properly fitted helmets. Hitherto, many aircrew had chosen to have a slightly oversized helmet, for comfort. But the airgap, especially when wearing spectacles, caused feedback; exacerbated by the acoustic chamber being smaller due to the PCB. The solution included a new design of earshell padding, and made to measure helmet fitting. (Which should be the norm anyway). The company had a [email protected] mapping system, which was simply fed to the machine that formed the helmet shell. Added a few quid to the cost, but worth every penny.

Edited to add image. There's a small rectangular thing sitting at 45 degrees to the tels transducer. That's the upper ANR transducer. This is the prototype, before the low profile one was fitted.




Last edited by tucumseh; 29th Jun 2020 at 06:11.
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Old 29th Jun 2020, 07:34
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I am currently running Bose A20 in an Evo helmet and the results are variable. Brilliant helmet, absolutely love it, and when the ANR goes good life is great. However, depending on the aircraft, and flight condition the buffeting from the ANR can drive you insane...

different helicopters cause different buffeting at different times. One Jet Ranger is fine with doors on, but hell with door off. Another Jet Ranger is really bad with doors on, but actually quite good with doors off....

The hueys all behave differently, one fully enclosed with a bubble window is beautiful no buffeting so really good. Another one is ok with the window in, and no good with window out, another is the opposite good with the window out and crap with the window in.

I wish i could figure it out, but i just swap between ANR and CEP helmet, depending upon what helicopter I'm going to fly, and what I'm doing.
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Old 29th Jun 2020, 08:04
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Thanks for all the info. I’m thinking safest bet is CEP.

D
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Old 29th Jun 2020, 09:09
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Originally Posted by donner89 View Post
Thanks for all the info. I’m thinking safest bet is CEP.

D
Much the same conclusion in many previous threads

ANR

https://www.pprune.org/rotorheads/289573-anr-headsets.html


Helmets - Should you? and Which?

https://www.pprune.org/rotorheads/364122-cep-communication-ear-protection.html
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Old 29th Jun 2020, 11:17
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Originally Posted by SuperF View Post
I wish i could figure it out, but i just swap between ANR and CEP helmet, depending upon what helicopter I'm going to fly, and what I'm doing.
As senior pilot says, this has been discussed many times. In the military case I mentioned (RN Sea King AEW Mk2), in 1994 the RN specifically rejected in-ear devices, which were the initial proposed solution.

But to your problem SuperF, depending on what type of ANR it is, it may be unrealistic to expect it to work in an aircraft it is not designed for. The Sea King ones were good for ASW and AEW variants, but not for the Mk4. Purely by coincidence, they worked in Sea Harrier. They were hopeless in Lynx, not too bad in Merlin but only for rear crew. Just minor component value changes to target the damaging frequencies in different aircraft, and let the frequencies you need to hear through.

At the most cheap and cheerful level, you can be sold a broadband system such as that used in the back of armoured vehicles. They don't have to worry about what you need to hear, and blot out most noise. The one above is the analog system, designed to meet the then 85dBA requirement. (Around 83 achieved). You needed a noise survey in each aircraft type/mark, and from that a variant of the PCB was developed. You either had a second helmet, or spent an hour changing the capsules. (And there has to be the same power source/connector). In the military, ANR presents a further problem - the helmet is no longer just an Aircrew Equipment Assy, it is a Comms System LRU, as it is aircraft powered and sits inside the TEMPEST boundary. And the associated curly leads were far more expensive that the ANR helmet.

Concurrently, a Digital ANR was developed to meet the new 75dBA requirement, and by 2000 had achieved around 71dBA. ISD was due 2001, but I'm not sure what happened as I was gone by then. That was programmable, so if you wanted to fly a different type one day, you simply plugged the helmet into a workstation and blew the EPROM for that aircraft. The next development milestone was adaptive ANR, which aimed to negate all that faff. I know it was successful - the same team at Farnborough did it - but don't know how widely it is used.

The answer to your problem is not straight forward, but hopefully I've given a few pointers on what to ask of your supplier.

I won't comment on Bose and ANR!
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Old 29th Jun 2020, 15:15
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Originally Posted by donner89 View Post
Thanks for all the info. I’m thinking safest bet is CEP.

D
You can have both. I've got a Gallet 250 built by Merit Apparel, with both ANR (small 9V system, not LS/Bose/DC) and CEP plug installed. When operating doors-off, CEP is the way to go with ANR turned off (simple flick of a switch on the rear). Otherwise, I'll skip the CEP, and just enjoy the ANR.

Another key to having good ANR performance with wind in the cabin is a very solid ear cup seal to your head. Make sure to spend time with the padding to ensure the seal isn't broken when you turn or tilt your head.
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Old 30th Jun 2020, 03:50
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Originally Posted by donner89 View Post
Thanks for all the info. I’m thinking safest bet is CEP.

D
If you want bomb proof CEP with the best noise reduction, look at getting custom moulded ear plugs with the HELO CHAIS. It uses the same CEP plug.
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Old 30th Jun 2020, 07:18
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Originally Posted by havick View Post
If you want bomb proof CEP with the best noise reduction, look at getting custom moulded ear plugs with the HELO CHAIS. It uses the same CEP plug.
What he said. I've got moulded plugs and they're awesome!
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