Active vs Passive sound attenuation

[tonyjeffs2]

I'm intrigued by a quote website selling ear protection -earplugs.

"Noise isolation (34-36 dB) far surpasses that of active noise-canceling earphones"

http://www.etymotic.com/ephp/er6.aspx

Surely that claim is impossible.
At the very least it could be classed as misleading if they're comparing their product with a very specific type of active noise reducer at a restricted frequency range.

Interested in any comments.

Tony

 

[GregLocock]

My experience with cheap on-ear (as opposed to around-ear) antinoise headphones is that you'd be lucky to see -20 dB (which is fine in context).

I don't think their claims are ridiculous. Performance of passive earplugs is well documented, why do you have a problem with those (very poorly defined) claims?

eg

http://annhyg.oxfordjournals.org/cgi/content/full/46/6/527

etc.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[tonyjeffs2]

I guess I took issue with the claim only because it was so poorly defined that in my view it could be misunderstood. If they had specified 'on ear', then their claim would be valid in the way you describe, but at the same time would be a somewhat inappropriate comparison since the main benefit of the active component of active headphones is to attenuate lower frequencies, which passive protection doesn't achieve very well.

It kinda caught my interest. I agree it isn't so bad.
Thanks for your thoughts on the subject.

Tony

 

[IRstuff]

These guys seem hardly to be people that would grossly mislead:

http://www.etymotic.com/aer/libart-year.aspx

Their academic bonafides seem to be quite strong.

TTFN

FAQ731-376

 

[GregLocock]

Well I'd be much happier if they gave a TL plot against frequency, rather than just posting the peak value.

Of course this raises the problem of bone conduction etc.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Rob45]

Maybe they just tested a sample of the available noise-cancelling headphones - which seem to focus their efforts more on being music players - and found their passive devices have "noise isolation (34-36 dB) far surpasses that of active noise-canceling earphones."

Which in my experience should be easy enough to do.