Noise and Hearing (was Re: [rescue] Re: Throw another packet on the server...)

[N.Miller]

On Saturday, August 23, 2003, at 08:43 AM, R. Lonstein wrote:

> On Fri, Aug 22, 2003 at 06:11:47PM -0400, Phil Stracchino wrote:
> 	[snip]
>> That's possible.  I do buy my helmets for a very snug fit, yes.  if 
>> the
>> helmet moves relative to my head when I shake my head, it's too loose.
>> I don't *think* the plug was touching the shell, but the liner could
>> have been touching the end of it.
> 	[snip]
>
> I noticed similar things with my old Shoei RF200 and sometimes with my
> HJC Symax with LaserLite plugs and those EAR yellow plugs. I have
> tried a bunch of different disposable and reusable plugs and only
> heard it with the Lites never with the Max or the reusables, which
> makes me think that they attenuate different frequencies. I like the
> Max plugs, YMMV.

I can show you an attenuation chart for silicone ear plugs; I
may be able to find similar for some variety of foam, too.  To
qualify for the ratings they have, they are tested by independent
labs to attenuate at certain levels across the frequencies.  They
usually attenuate high frequencies better than low (that's why
they make concerts sounds so flat--and why they make special
low-end filtered ear plugs for non-musicians to wear at concerts).

I formulated the vibration transfer theory after my empirical
experiments with trimming my own ear plugs.  Having no problems
with foam ear plugs while getting the buzz with the silicone ear
plugs that fill my ear bowl led me to try it.

=Nadine=