[Martin Butt]

Hi,
I have purchased some noise cancelling headphones to listen to
music on the train to work. My reason for buying them is to prevent the
damage caused by listening to my music loud enough to block out the
sound of the train. I am under the impression that noice cancelling
technology works by listening to whats going on outside and having the
reverse sound waves played through the speakers, thus cancelling the
sound waves. My question is, do the sound waves actually get cancelled,
and therefore can't cause hearing damage. Or actually, are they still
there, even louder, but unaudiable? I know that when I am at very noisy
stations, it feels like there is intense sound "pressure" on my ear
drums, even though I can't hear anything. Am I worrying over nothing?

Cheers,
Martin

 

[Homer J Simpson]

Am I worrying over nothing?

Yes. The phones probably can't cancel the really low frequencies
('pressure').

 

[Brendan Gillatt]

Hi,
I have purchased some noise cancelling headphones to listen to
music on the train to work. My reason for buying them is to prevent the
damage caused by listening to my music loud enough to block out the
sound of the train. I am under the impression that noice cancelling
technology works by listening to whats going on outside and having the
reverse sound waves played through the speakers, thus cancelling the
sound waves. My question is, do the sound waves actually get cancelled,
and therefore can't cause hearing damage. Or actually, are they still
there, even louder, but unaudiable? I know that when I am at very noisy
stations, it feels like there is intense sound "pressure" on my ear
drums, even though I can't hear anything. Am I worrying over nothing?

Cheers,
Martin

A review by 'The Gadget Show' a while back (channel five, UK) showed
that passive noise canceling phones perform better and are cheaper. They
have expanding rubber on the end which fills the ear to stop ambient
noise. You can pick up a good pair for around £60 ~ $115.
Also see these:-
http://www.advancedmp3players.co.uk/shop/product_info.php?products_id=307
they fit on the end of your regular earphones to give a similar effect.

 

[Martin Butt]

You could always ram a pen down your ear hole, cancelling all sound,
ever again.

 

[Mike Meakin]

You could always ram a pen down your ear hole, cancelling all sound,
ever again.

But there surely is an idea !

Sound can be conducted through the bone in the head (just try tapping your
teeth with a pen !)

A small 'piezo' disc transducer held onto a tooth and fed with anti-phase
ambient sound might just cancel that heard by the ears ?

It's Sunday morning and I am almost inclined to give it a try !

Just Googled for 'tooth microphone' and found:

http://www.engadget.com/2005/09/29/tooth-microphone-patent-filed/

 

[Don Bowey]

But there surely is an idea !

Sound can be conducted through the bone in the head (just try tapping your
teeth with a pen !)

A small 'piezo' disc transducer held onto a tooth and fed with anti-phase
ambient sound might just cancel that heard by the ears ?

It's Sunday morning and I am almost inclined to give it a try !

Just Googled for 'tooth microphone' and found:

http://www.engadget.com/2005/09/29/tooth-microphone-patent-filed/

Bone conduction headsets have been available for many years. The earphone
is also the microphone.