Measures attenuation
February 1st 2008 For many years there has
been a debate regarding the
relative merits of various
calculation methods for the
estimation of the degree of
protection provided by
hearing protection devices.
No two users are the
same; we all fit hearing
protectors (particularly earplugs)
with varying degrees
of skill, and we all have
different facial shapes and
ear canals. Attempts are
made to account for or allow
for these differences. The
Standard Deviation figures,
which are provided for all CE
marked products, are
calculated from the test
results for a panel of users
and indicate how widely the
results differed from the
average (Mean) attenuation.
Using the Octave Band
Analysis is a good indicator
of what a user is
likely to
achieve, but
it remains
an
estimate.
The
point,
says Aearo,
is that we
are trying to establish what
protection a user is going to
get and we are 'going round
the houses' to get there.
Logically, we should be
measuring what the user has
achieved, not estimating.
The E.A.RFit system
measures the attenuation
achieved by an individual
when they have fitted their
own ear-plugs directly.
The ear-plug is probed; it
has a fine flexible tube
through it that allows
measurement of the noise
reaching the inner ear. One
microphone measures this
level; a second measures the
noise outside.
From these two levels, it
is possible to calculate the
protection achieved by the
individual with ear-plugs
they have fitted themselves. More articles from 3M UK Plc: | 
