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Helmet noise


Dave McReynolds

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Dave McReynolds

I would buy a new helmet costing anything up to $1,000 if it were truly silent. That is, if I could ride long distances without needing earplugs, and if my somewhat deaf old ears could hear music and radio programs through Blue Tooth helmet speakers rather than having to use custom molded earphones or turn the volume way, way up. I assume some of the rest of you would be willing to pay that much too.

 

Which leads me to wonder if the helmet manufacturers are really trying as hard as they could to accomplish that? I mean, there are some environments that are a lot noisier than a motorcycle, particularly a BMW, and people wear hearing protection that seems to work. For example, when I go to shoot my pistol, I wear headgear that brings the noise down to a dull pop that costs less than $50.

 

I am not normally a conspiracy freak, but it has occurred to me that maybe helmet manufacturers have reduced the noise as far as they are willing to go. That if they reduce the noise any further, they feel they might be liable for any accidents that might happen because we didn't hear something.

 

Do you think that could be the case, or do you think they're trying as hard as they can, and the current crop of helmets is the best they can do?

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Coincidentally Dave, I was just taking my Arai apart to clean it and put in Iasus speakers that will only be used for radar plug in when I deem in necessary....Tried the speakers earlier with i-Pod and just couldn't hear well enough, and Arai's are known for being noisy helmets....I really like my Quantum II though it does allow a lot or racket in there...So, I wear ear plugs or ear buds when using the GPS...

But thinking about your comments and wishes for a really quiet helmet, I wonder if it could be truly soundproof without making it also ventilation proof and therefore allow heat to build up in there?...

Would be interesting to hear what the folks at Arai or Shoei have to say about noise and what their approach to it is when designing these things....Your speculation about fearing getting too quiet might be correct......

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Dave McReynolds

I wonder if it could be truly soundproof without making it also ventilation proof and therefore allow heat to build up in there?...

 

I was thinking about that too, but I would be happy with having my ears isolated, and maybe sweaty, if the rest of my head could be ventilated.

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There is no such thing as a quiet helmet. There are hardly any such things as much quieter helmets. Each helmet maker claims his is quiet but that never holds up in our buy it before trying it business. It is particularly a problem for those of us that are tall, riding bikes with fairings.

 

It is much less a problem for those with unfaired bikes (see below) as the helmet system then operates in a free undisturbed field.

 

Most of the noise problem from faired bikes is that the helmet shell vibrates in response to aerodynamic forces. Most of us ride behind a fairing, which has a turbulent blowoff around the fairing edges. That blowoff causes the helmet shell bottom to vibrate - much like a bell. Our ears are inside the "bell" and we interpret this as noise.

 

Note that it sounds like the noise is originating inside the center of your head, in contrast to being an uncorrelated noise at each ear. This is because the shell motion is in and out simultaneously beside each ear. If you could see the motion of the helmet at the bottom, you'd see the front and back going in and out while the ear areas go out and in at this natural frequency.

 

What is needed would be a constrained layer damping strip around the bottom of the helmet, but I don't know how to create one that would be effective over a range of temperatures. Google Dyad and Soundcoat for further description of this technique.

 

I have found that if I compress a helmet very tightly onto the top of my head with a free hand, the roaring noise goes away. In this case, my head and skull is serving as a stiffening reinforcement of the helmet shell structure, suppressing the vibration.

 

Another possibility would be to perforate the helmet shell with many holes around the ear areas so that there wouldn't be as much air piston effect on our eardrums. I was going to do this with an old helmet, but a virus took out my hearing last January such that I can't really diagnose much any more..

 

Of course another sound source is the wind whistle immediately below our ears from a non faired bike. That can be taken care of with various neck warmers etc.

 

Anybody else have observations or thoughts?

 

MN Engineer - retired

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I am not an engineer, nor do I know very much about speakers or anything electrical so I have no idea if this will work or not.

 

This is not an advertisement nor do I know these guys, etc.

 

I have been in aviation for 25 years or so. Headsets come and go. There are the clamping tight kind, and there are the ANR kind. For the last dozen years or so I have used BOSE ANR headsets in my personal airplane which is very loud. I listen to music, converse with the other passengers, here ATC, etc without problems. It is far better than ear plugs.

 

I am going to order one of these kits http://www.anr-headsets.com/Html_folder/HelmetKitOrder.shtml

over the winter and attempt to install it in one of my older motorcycle helmets. They claim it works in helicopter helmets and if it does, it may work in mc/helmets.

 

The problem for me is not being an electrical genius and not knowing the difference in speaker ohms, etc..it will truly be an experiment.

 

I will post results in February or so..you know when the weather is too bad to pleasure ride and I am bored stiff.

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I am willing to help re: electronics questions if you want. I am very interested in ways to hear better while protecting my ears. I currently use a Shoei RF-1000 helmet which I did a lot of research before buying to be among the quieter helmets. As has been said above the immediate environment makes a lot of difference in noise levels.

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Skywagon - I have installed and used two of their kits in aircraft David Clark H10-40 headsets. They use an analog control scheme (unlike all other ANR headsets) and it was very effective for that application. I think that an analog ANR will work better for our type of noise which has a broader band random noise to be rejected) than will any digital ANR.

 

From their limited published specifications I thought there might be sufficient transient response of their system to reduce noise of typical helmet buffeting frequencies by several db. However, you may have to plan on adjusting the gain of their system to optimize the response for a helmet environment, which will have different system characteristics than an aircraft headset. There is a potentiometer on each of their circuit boards. I presume this would be the ANR control loop gain adjustment. If it squeals unbearably, you have too much gain, but there may be more things that can be done.

 

I e-mailed Headsets Inc about M/C applications a few years ago, but never was able to get any response from them. See if you can get HI to help you with this application of their stuff. I struck out with them and gave up.

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Good thread. I too am at the starting point on a search for a quiet(er) helmet.

 

I was just mulling over the question and toss this into the mix. What about some sort of, for lack of a better term, neck-roll baffle thingy that nestles up against the bottom of the helmet? It would have to be of some sort of material that does not get too hot in the warm months.

 

I could go on, but you get the idea... anyone know of such a device or are we going to have to invent it?

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great thread.

 

In regards to a neck device- Webbikeworld says the 'Windjammer' is effective: http://www.webbikeworld.com/motorcycle-helmets/helmet-noise.htm

 

They also have sound files on the same page (scroll down) of actual recordings of different helmets. Seems we all are searching for the same thing. I too would be interested in something to make my ride more pleasant.

 

The RT just flat pushes a bunch of air to make its way through the world. Last month I rode both my bikes around the block (2.5 miles) without a helmet just prior to a TB synch. Believe it or not my '79 Triumph Bonneville was quieter (for the rider)than my '99 RT.

 

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Unbelievably I am doing research on this very subject using four old helmets. While still in the preliminary stage these factors appear to dominate: (not in order of importance)

 

1. Uneven surfaces over the ear area outer surface.

2. Open areas at bottom of helmet.

3. Hard surfaces on outside of helmet.

4. Lack of sound absorbing materials over ears inside.

5. Uneven surfaces over other areas of helmet.

6. Poor windshield air control.

7. Poor visor seal and or uneveness.

8. Bike noise excessive, motor and or fairings.

9. Tire noise excessive.

10. Wind speed and direction. Essentially uncontrollable.

 

Solutions to this problem will have to address all of these problems. I am looking for funding sources to quantify these factors. At present I am going for rides and using my ears instead of using a wind tunnel and microphones!! If anyone knows of some entity that might fund this research please let me know. To do it right would be about $15,000! I have one helmet that is approximately half? as noisy? as when I started with only minimal weight gain and greater comfort. It is, however, very ugly since it has been modified so much.

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I have found some neck warmers that sharply reduced the noise for unfaired bikes, but others that seemed similar, did not. The only apparent difference was the total weight and density of the neck warmer material - heavier seemed better, which makes sense from an acoustic standpoint.

 

Neck warmers do almost nothing to reduce noise on a faired bike. For them to be effective, they have to be in a non-turbulent flow.

 

The helmet-to-jacket "gasket" for unfaired use is something that should be explored further.

 

The overall quietest riding combination seems to be one or more neck warmers on an unfaired bike, with tape at the top of the visor to fill the gap.

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In my limited opinion, I think the problem is with the lack of seal around the ear. After wearing an SPH4 flight helmet (and ear plugs) for years working around helicopters and jet engines, it is no less than amazing the amount of noise attenuation provided by that helmet (appropriately fitted) and ear plug combination.

Wearing such, the head could be place near a running jet engine that would produce severe ear pain when the earcup seal around the ear was broken and still be able to hear through the speakers. With the same combination, one could poke their head out the door at 100+ kts and still be able to converse with ease.

 

A Nolan N100 in combination with ear plugs and a Slik provide a quiet enough environment for me to hear a satellite radio through Chatterbox speakers. Not as quiet as I'd like, but sufficient. My complaint is the lack of weather proofing. Haven't found a helmet yet that wouldn't fog or would keep out a driving rain for more than a few minutes. You'd think by now these sort of complaints would be history.

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Been dealing with a combination of helmet buffeting/noise, on my Vstrom. During the summer I use a "very" low windscreen that allows smooth airflow around my helmet with out buffeting, but I need to wear ear plugs at high speed because of the air flow noise. My wife riding on the back said I block much the air flow giving her a lower noise ride. We both wear full face helmets.

 

Installed a Rifle +5" over stock height windscreen for the winter and found one setting to reduce most buffeting and high level of noise. Still had some buffeting at high speed that caused helmet rattle/vibration and buffeting noise. While riding down the road, I grabbed the chin strap and pulled down at high speed. Reduced helmet buffeting rattle/vibration and buffeting noise enough to make a very pleasant ride. Switched helmets with my wife and resolved some problems. Both of our helmets are the same size but from different manufacturers. Her helmet fit me tighter without discomfort reducing the helmet buffeting rattle/vibration and much of the buffeting noise. My helmet is a looser fit which is more comfortable without any buffeting for her with less noise than the lower summer windscreen.

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Unhofliche_Gesundheit

wow interesting. 300 ohms is a lot of ohms! :/ normally we see 8 or 16. quick look on the internet suggest hi impedance used so bunch of headsets can be run in parallel (say the entire flight crew..)

is this the theory?

so how would you get around the large impedance missmatch? electronics needed i would wager?

 

i am very happy to read the above thread - i though i was alone in my total displeasure of the amount of noise i have to put up with. :eek: Cal-Sci +6" windscreen + full face (with many large scoops) + earplugs = still too loud! :dopeslap: i mean STILL TOO LOUD ! i am not happy that you are also suffering but rather sounds like the assembled talent might be able to come up with a fix. :)

 

let us know skywagon how the NC headphones work out. hope to read about it here.

:lurk:

& thanks for the tricks - i will try to dampen the resonating bell that is my helmet ( via strap down force, and balaclava - the weather now allows for this) and try some taping.

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This is a very interesting thread. Noise is something I'd like to reduce in all my helmets.

 

I currently have a one year old HJC AC-3 open face helmet and a 2 year old Scorpion EXO-700 full face helmet. I don't have any empirical data, but to me the open face AC-3 is much quieter than the full face Scorpion. That seems contrary to logic, but I have noticed it more than once. I almost always use ear plugs now, although often only on one side. The other side is pretty deaf already due to illnesses and infections when I was younger, and flying around in airplanes for 30 years in the Navy didn't help.

 

Can anyone explain that?

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Dave McReynolds
This is a very interesting thread. Noise is something I'd like to reduce in all my helmets.

 

I currently have a one year old HJC AC-3 open face helmet and a 2 year old Scorpion EXO-700 full face helmet. I don't have any empirical data, but to me the open face AC-3 is much quieter than the full face Scorpion. That seems contrary to logic, but I have noticed it more than once. I almost always use ear plugs now, although often only on one side. The other side is pretty deaf already due to illnesses and infections when I was younger, and flying around in airplanes for 30 years in the Navy didn't help.

 

Can anyone explain that?

 

I think an open-faced helmet will often be quieter than a full face helmet, since the open-faced helmet is sealed around the head and face, whereas the full face helmet is open at the bottom, which often acts as a scoop for the air flowing up the body.

 

I found the earlier comments about the helmets used by carrier flight deck crew members interesting. If a helmet can be designed that will insolate against the ear-splitting noise of a jet engine, catapult, etc., then surely one can be designed to insolate us against the noise of riding on a motorcycle.

 

If we ever do get a really quiet helmet, a nice feature to have would be a switch to allow us to hear the ambient noise, so we can flirt with the toll gate attendents, etc. This shouldn't be much of a problem since I want mine wired for sound anyway. Just something that would turn on a mike to the outside.

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While riding down the road, I grabbed the chin strap and pulled down at high speed. Reduced helmet buffeting rattle/vibration and buffeting noise enough to make a very pleasant ride.

I have found that it is necessary to pull down very strongly to reduce the shell vibration - so much that it would be comfortable only for a few seconds.

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The random roaring sound from fairing blow off with a full face helmet has frequency content to maybe only a couple of hundred Hz, and I suspect may be peaked at only about (80 Hz my guess).

 

This means the wave length of the sound is like 10 ft, which means that any effective absorbing media will have to be a moderate fraction of 10 ft thick to absorb the resulting pressure waves. My guess from that is that a foam thickness of only say 1 inch won't be very effective to reduce the sound pressure from shell vibration at those frequencies. If the frequencies were a l ot higher, it might be possible. The low frequencies of a shell first mode vibration in the bell mode is a lot of our problem.

 

The sound pressure from a jet engine has much higher frequency components in it, where passive sound absorption materials would be more effective. I'd sure like to see one though to figure out why.

 

I also suspect an open face helmet might be quieter because the vibration mode nodes (i. e. the place of maximum motion amplitude) would be less concentrated immediately adjacent to the wearer's ears, and there is more of an escape path for the resulting pressure wave.

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Dave McReynolds

The random roaring sound from fairing blow off with a full face helmet has frequency content to maybe only a couple of hundred Hz, and I suspect may be peaked at only about (80 Hz my guess).

 

To a non-techie, that sounds like the vibration I feel from hip-hop playing in an amped-up car a half-block away. While annoying in its own way, that wouldn't interfere with voice or music, which I assume are much higher frequencies. What I would like is to have insulation from the noises that prevent me from enjoying music or voice sounds.

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OK.

 

So we start with a Shoei Multitec flip face in carbon fiber, of course. So I can put a bag of cherries on my lap and spit the seeds as I go. Carbon fiber cause we want it light. and cool. :Cool:http://www.webbikeworld.com/r2/shoei/multitec/

 

Have it made with Bose noise cancelling headphones, so we hear only our music, unless we hit the switch. http://www.bose.com/controller?url=/shop_online/headphones/noise_cancelling_headphones/quietcomfort_2/index.jsp

 

It must have the Akuma Electrochromatic visor: http://webbikeworld.magnify.net/video/Akuma-Electrochromatic-Visor

and tail lights and map light of the Akuma Ghost rider: http://www.webbikeworld.com/r2/motorcycle-helmet/akuma-helmet/

 

No phone jacks please, who do we want to talk to?

 

The perfect helmet.

 

Now if I only had any gas money left I could go RIDE. :wave:

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Both my Arai & Scorpion fullface helmets are much quieter with the face shield open. A poor sealing shield seems to be a major source of noise.

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Some aviation-type passive (i.e. non-ANR) headsets provide excellent noise protection too. My relatively inexpensive Lightspeed headset, used in an ultralight aircraft (read: extremely loud) provides a comfortable level of quiet, better than any earplugs I've ever tried. It depends for its effectiveness on a good fit of the soft rubber seal around the ear. The technology would work great in a helmet if the problem of putting it off and on could be solved -- it needs to be spread apart to insert your head, then allowed to clamp back together for a good seal. I suspect this may be true of ANR headsets too. If someone could figure out a way to do that, we might have a breakthrough . . . :grin:

 

Lee

2002 1150RT

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If we had a helmet that opened and closed like a clamshell... with the hinges on top of the head and well... you get the idea.

 

I have ear protectors in my shop that also have been used on the gun range. Effective but not very stylish. Maybe we could cut big holes in the helmet and wear the ear protectors over it...

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It depends for its effectiveness on a good fit of the soft rubber seal around the ear.

 

I've often thought that the solution would be some kind of inflatable seal that you pump up with a small squeeze bulb and release with a twist valve. Think of a donut that surrounds your ear, attached one side to the helmet, that you could inflate to your desired pressure once your helmet is on.

 

Anyone have the tools and meterials to prototype one of these?

 

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I believe the answer is in a modified helicopter/motocycle helmet.

 

Seems we need to isolate the ears from the BELL effect of our helmets with a small dome over the ear to allow for a foam enclosure to fit. Then speakers or earbuds should work.

 

I have a cheap one piece full face helmet, might experiment with grafting on some domes, maybe shooting protectors or something. Gonna be ugly tho.

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Dave McReynolds

I've often thought that the solution would be some kind of inflatable seal that you pump up with a small squeeze bulb and release with a twist valve. Think of a donut that surrounds your ear, attached one side to the helmet, that you could inflate to your desired pressure once your helmet is on.

 

That sounds like a great idea!

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The key to the blowoff noise problem will be some way to 1) isolate the ear cavity from the vibration of the helmet shell, 2) provide enough damping in the helmet shell that it does not vibrate from turbulent air flow impacts, or 3) provide an active noise cancelling (ANR) system.

 

None are very technically straight forward since the wavelength the noise pressure wave is several feet yet the frequency is substantial.

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I've often thought that the solution would be some kind of inflatable seal that you pump up with a small squeeze bulb and release with a twist valve. Think of a donut that surrounds your ear, attached one side to the helmet, that you could inflate to your desired pressure once your helmet is on.

 

Scorpion has a helmet model that is inflatable. I think it's the 1000 model.

 

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