March-12-1995
A warning to people about hearing protectors:
I had a set of those custom molded ear plugs made a while back. I noticed that they seem to have less attenuation than the standard throw away EAR foam plugs, but I didn't think it was significant.
I recently participated in a hearing test that measured in use attenuation of various hearing protection.
The custom plugs come out _very_ deficient in the low frequencies, thus they can act as a very significant avenue to hearing loss.
Here is the table:
Attenuation @ Frequency
Protection 8k 6k 4k 3k 1k 2k 500 250 125
------------------------------------------------
Custom plugs 36 31 31 35 33 19 12 11 12
Muffs (Bilsom) 23 21 27 27 28 25 23 9 1
EAR Foam 35 34 36 35 36 40 43 35 29
EAR Caboflex 33 33 33 38 34 26 27 25 25
(canal Cap)
Muff+EAR Foam 41 38 42 46 38 44 47 34 28