From: utzoo!decvax!cca!hplabs!hao!menlo70!sytek!zehntel!teklabs!donch@sri-unix
Newsgroups: net.cycle
Title: Re: headphones and helmets
Article-I.D.: teklabs.1391
Posted: Wed Sep 15 12:39:28 1982
Received: Wed Sep 22 11:04:05 1982

Recent discussions here concerning headphones and helmets brings to mind
a discussion I had with a grad student audiologist.
  
This fellow was a grad student at Portland State University (Oregon) several
years ago and was doing massive testing of people chosen at random for
his thesis.  He told me that one result of his tests was to be able to 
identify a motorcyclist based solely on  the standard full-spectrum
audio test.  Apparently cyclists have reduced sensitivity in a particular
region of the sound spectrum.  His conclusion was that motorcycles were
terribly loud machines, hence a danger to hearing.  As most of you know,
the engine is invariably drowned out by wind noise at speed, and it is this
that certainly causes the reduced sensitivity he noted.

My experience over the past 15 years has prompted me to use the expandable
foam type ear plugs whenever I take a protracted ride.  It saves me from
a very obvious hearing suppression that otherwise occurs whenever I
don't use earplugs on long trips (> 1 hr.).

For many years my helmet of choice was a Bell Magnum.  When I finally
bought a Nava (it was the only full-coverage helmet to fit my strangely
shaped head), the noise reduction was enormous.  The Magnum let an
incredible amount of self-generated noise in.  Wearing glasses compounded
the problem because it destroyed the padding seal in front of the ears.

I bought a cheap set of "Walkman" type earphone that will fit in the space
available in my Nava.  They haven't been installed yet largely because
of hearing-loss concerns as described in previous articles.  The point
is important on these type of phones because they are specifically designed
not to mask external sound.  Earphones that completely surround the ear
and seal to the side of the head DO mask sound and should be the phones
of choice for ear-conscious people.  However, I haven't found any that fit
inside my helmet or that I'm willing to gamble bucks on for an experiment
after cutting them up to fit.

Perhaps the main point of all this is:  hearing loss is insidious.
And once it occurs, you don't get it back in almost all cases.
Food for thought.

                            Don Chitwood
                            Tek Labs, Tektronix