I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan

On 10 Oct 2003 06:49:19 -0700, (Ethan Shayne)
wrote:

I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan

No - can't be done.

d

_____________________________

http://www.pearce.uk.com

Actually it can be done and is often done in test labs and other places.
However, it is extremely expensive and location specific. Basically, you can
acoustically cancel sound in an area of a few cubic meters, but the affect
outside of that area will be more noise than you stared with.


"Don Pearce" wrote in message
...
On 10 Oct 2003 06:49:19 -0700, (Ethan Shayne)
wrote:

I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan

No - can't be done.

d

_____________________________

http://www.pearce.uk.com

I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan


Lotus through GM was working on such a system for automobiles and they had
limited success with it.

It requires some real fast computation and only works in a small environment.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty

On Fri, 10 Oct 2003 14:50:01 GMT, "flint"
wrote:

Actually it can be done and is often done in test labs and other places.
However, it is extremely expensive and location specific. Basically, you can
acoustically cancel sound in an area of a few cubic meters, but the affect
outside of that area will be more noise than you stared with.

Strictly limited to frequencies whose wavelength is large compared
with the space being treated.

d

_____________________________

http://www.pearce.uk.com

In article ,
Don Pearce wrote:

I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan

No - can't be done.

And, it can be dangerous to try. See "Silence Please", from Arthur C.
Clarke's "Tales from the White Hart", for evidence of this.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Acoustical noise cancelling is very critical, and experimental. It is
mostly being done in labs under controlled conditions. There are several
aircraft companies that have been using it under controlled basis to cancel
out engine noise, but under fixed conditions of distance and the angle of
direction that the sound would be traveling in.

There are a few manufactures that make precision acoustic noise cancelling
devices incorporated in to some models of aircraft communications equipment.
Apparently, it is not always effective, and the person using it is
constantly tweaking it to try to make it work well.

Semiens does make a pair of headphones with an acoustic receiver that also
contains a microcomputer device This unit takes in outside noise, and tries
to keep it adjusted to the proper level an phase that is arriving to the
wearer's ears in relation to the outside noise.

I have no idea if this unit is only experimental, or if it is on the market.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Ethan Shayne" wrote in message
om...
I've heard about noise-canceling headphones. Do devices exist that
operate on the same general principle, but operate more like speakers
than headphones? In other words, something that could sit on the floor
or a table to dampen general noise throughout a small room?

Thanks,
Ethan

I heard that they had a unit in a car a few years ago to get rid of engine
noise but it was so succesful people didn't realise when they had mashed
gears and when their engine was in trouble... Also I recently tested a pair
of sony headphones with a noise cancelling device built in and was not
impressed at all, it just sounded like I was underwater.

I heard that they had a unit in a car a few years ago to get rid of engine
noise but it was so succesful people didn't realise when they had mashed
gears and when their engine was in trouble... Also I recently tested a pair
of sony headphones with a noise cancelling device built in and was not
impressed at all, it just sounded like I was underwater.