From: lmcstst@noah.ericsson.se (Stamos Stamos)
Newsgroups: rec.motorcycles
Subject: Re: Earplugs
Date: 1 Sep 92 18:49:36 GMT
Organization: Ericsson Communications Inc. Montreal, Canada

In article <1992Sep1.141625.910@colorado.edu> matthews@ajsh.colorado.edu (Alex Matthews) writes:
>>>
>>
>
>Here are ProTech's ratings for its various types of plug.  I have no idea 
>what the composition of some of these are. 
>
>type              NRR (db)
>----              --------
>soft vinyl         23
>soft wax           24
>soft tone          26
>air cushion        27
>soft foam          33
>
>The NRR is used for comparison purposes only, like the EPA mileage ratings
>for cars.  Subtract the NRR from the A-weighted environmental noise level
>to get the approximate level of noise entering the ear, in dbA. 
>Actual attenuation varies as a function of frequency, though, which 
>explains why a plug with a lower rating may work better in some cases.  
>As always, be aware that a very good earplug may reduce traffic noise
>below your threshold of hearing; if this happens you should consider
>a plug with a lower rating.
>
>(I used to think the cylindrical foam plugs were good, until I tried the
>ProTech Sof-Foam plugs, the neon orange, contoured ones.  I ran out
>of them this week and had to use some cylindrical ones, and felt like
>I was being tortured!  A testimonial, dear friends. I paid $0.83/pair
>for the ProTechs)
>-- 



Yup, I hate the foamy yellow thingies. It may have NRR of 33 db, but inside
a helmet that could be NIR of 33 db (Noise Increase...

When I first had to start using(had too because I bought this used CBX550
with a straight-through pipe, but that's another story...), I used the yellow
foam cylindircal ones. At the end of each trip my ears would be ringing like
crazy. In fact my ears would ring much less if I didn't use the ear plugs. I
couldn't understand it because with plugs in and helmet on it was much quieter.

What happens is that these foamy thingies are made to compress with your
fingers allowing them to be inserted into the ear, then they slowly expand.
The problem is that they keep expanding out off your ear and touch the helmet
(also they are much to big for 'inside-the-helmet' use). No matter how I 
inserted them they always expanded to the point where they just stick out of
your ear. This makes for a magnificent acoustical coupling between your ear
drum and your helmet.
As the helmet is buffeted by the air/bugs it moves/hits the foam. This can have
your ears ringing in no time. If you don't believe me, try it. Insert the
foamy thingies in your ear wait a bit then tap them VERY lightly with your
finger, they will sound very loud.

I think they should come with a WARNING:
                                        If you use these while wearing a 
                                        helmet you probably will damage your
                                        ears!


I have found the waxy ones(for swimming) to be the best inside a lid.
The disadvantage of these is that every time you use them a bit of wax is
lost.  Other things you can do to make things quiet at (ummm) 'highish speeds' 
are:
A) Use a quiet lid. (ya right)

B) Use a ski head band type thing around your ears then
   put your helmet on.

C) Compleatly seal the face screen with thin velvet strips that
   stick on one side.

D) Attach a thick cloth/leather in between the helmet lining and the
   helmet shell, from ear to ear and tuck into top of jacket collar.

If you go for C or D then you will have to use anti-fog stuff on your screen.

Due too the fact that I would like to keep my hearing in the upper frequency 
range(as your ears are damaged you hear fewer and fewer frequencies, back
at school our class connected a sine wave generator to a speaker, most people
could detect the sound up to 14~16 khz, the teacher bombed out at 9khz(deaf bat)
remember that next time you spend that $1,000 on speakers that go to 25khz)
I use all four methods above. (ummmm, that doesn't mean I speed.) 

Performance Bikes did a noise test on lids at 70mph(I think), they all were
in excess of ~125db. (I am a bit sketchy on the figures, I should look the
article up). I think this is in the range of immediate irreparable ear damage.
Does anybody have the exact figures???

I wonder what you would get at 140mph. (ummm, not that I have ever gone that
fast)


Anyway I find that all this padding still allows you to hear whats going
on around you without going deaf. The ear(a marvelous thing, the ear) in few
minutes (you do warm your engine up before riding, don't you?) will have
adjusted to the ear plugs. My hearing is now up near the no plug level,
just that now the pressure waves on the ear drum are greatly reduced. This 
happens, as at the end of the trip when I remove the plugs I very sharp hearing
for a few minutes.



Some amazing but true facts I remember from school:

3db increase is a doubling of the sound pressure/volume.

To decrease the reading by 3db you have to double your distance from
the noise source. 



okay wake up now.





--
Stamos <lmcstst@noah.ericsson.se>            ZZR11            Ellas
Ericsson, Cellular Design
Montreal, Canada.
Newsgroups: rec.motorcycles