Ear plugs have reasonable leakage factored into them. The dB noise gain
figures are still added.

The bone conduction you mention is real but not a factor in cochlear damage
as the frequency range conducted is not a problem and cartilage tends to not
conduct as well.

Any sounds conducted thourh your musculoskeletal system of that magnitude
would give you more than just cochlear damage. We are talking airborne noise
here and the medium density impedance change is not conducive to
transmitting noise this way. If you are talking jack-hammer vibration then
we have a concern. Being that is not the topic of this group the rest is
just nonsense.

wrote in message
...
You discount sound leakage around the ear canal. At 30dB, you're down a
factor of 1000. Conduction through the jaw bone and through the throat
passage into the inner ear become significant, which is *not* taken into
account by the muffs or plugs. The added "protection" isn't. There is good
reason there aren't products out there that are much better than about 35dB;
can't happen.

On Wed, 16 Jun 2010 22:47:25 -0400, "Josepi" wrote:

dB measurements do add linearly.

Not for ear protection they certainly do *not*.

It is a relative logarithmic scale that
makes calculations easy for audio and small signal people to express and
calculate.