Hearing Protectors

[Jory A. Olson]

You'll have to explain your statement that "A harmful noise level without use of a noise cancelling device is just as harmful with the use of one."  The headphones sample the noise arriving at the microphones in the earpieces.  The transducers in the headphones then cancel out the sound going into your ear.  There is nothing "perceived" about it; it's quite real.  The only sound that doesn't get cancelled out is due to the non-linearity of the microphones and the transducer's, the slight difference between the sounds arriving at the microphones and those arriving at the ear, and the time delay involved in processing the signals from the earpieces.  

Noise cancellation headphones generally do better than foam earplugs and headphone type hearing protectors.  They will not eliminate ALL of the noise, but they do better than 30 dB offered by the alternatives. 

There is nothing "magic" about noise cancellation headphones.  What you hear is still what you hear.  If something still sounds loud while wearing the headphones it is.  

Please explain "if the level is high enough to damage hearing without use of this device it will still damage it even though the device is used" it does not make sense based on my knowledge of how the headphones work and my personal experience.

Jory


Date:	Fri, 16 Oct 1998 11:33:03 EDT
From:	JIMRPT@aol.com
Subject:	Re:  Hearing Protectors

<<noise cancellation headphones>>
Et Al;
A word of caution is needed here, in my opinion, since several have mentioned
these devices.  What the noise cancellation device does is reduce the level of
perceived noise and not reduce the level of noise. A harmful noise level
without use of a noise cancelling device is just as harmful with the use of
one.  They are extremely useful for cancelling perceived noises and use of one
will allow one to feel fresher after exposure to noise than being exposed to
the same noise without one but..........if the level is high enough to damage
hearing without use of this device it will still damage it even though the
device is used.  I love these things but......... use them with knowledge and
caution please.
Jim Bryant (FL)

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