Cancel noise/voice/sound coming from one direction

[terry]

Does it exist a device used to cancel the noise/voice/sound coming
from one direction when I installed it?

 

[John Popelish]

Does it exist a device used to cancel the noise/voice/sound coming
from one direction when I installed it?

Sort of. Google [noise cancellation]

Since sound propagates at a particular speed through air, it is
theoretically possible to mic the sound coming from some direction and
amplify that, reverse the polarity of the pressure wave and launch
another wave that arrives at your ear equal and opposite from the
original sound. But if you move your ear, you have to set it up all
over. It is not practical to cancel the sound over an extended area,
unless you emit the canceling sound at the same place that the
original sound is emitted.

 

[terry]

Sort of. Google [noise cancellation]

Since sound propagates at a particular speed through air, it is
theoretically possible to mic the sound coming from some direction and
amplify that, reverse the polarity of the pressure wave and launch
another wave that arrives at your ear equal and opposite from the
original sound. But if you move your ear, you have to set it up all
over. It is not practical to cancel the sound over an extended area,
unless you emit the canceling sound at the same place that the
original sound is emitted.

Do u know whehter there exists such a product in the market and can be
bought through internet?

Thanks!

 

[Robert C Monsen]

Sort of. Google [noise cancellation]

Since sound propagates at a particular speed through air, it is
theoretically possible to mic the sound coming from some direction and
amplify that, reverse the polarity of the pressure wave and launch
another wave that arrives at your ear equal and opposite from the
original sound. But if you move your ear, you have to set it up all
over. It is not practical to cancel the sound over an extended area,
unless you emit the canceling sound at the same place that the
original sound is emitted.

Do u know whehter there exists such a product in the market and can be
bought through internet?

Thanks!

Pilots like to use noise-cancelling headsets in small planes and helicopters
(which are particularly loud.) You can buy them from various places. The
placement of the feedback mics is pretty critical. I had a pair that would
occasionally start squealing when I started an approach. My guess was an air
pressure issue, causing the headset to shift slightly, causing positive
feedback.

Regards,
Bob Monsen

 

[MK]

Sort of. Google [noise cancellation]

Since sound propagates at a particular speed through air, it is
theoretically possible to mic the sound coming from some direction and
amplify that, reverse the polarity of the pressure wave and launch
another wave that arrives at your ear equal and opposite from the
original sound. But if you move your ear, you have to set it up all
over. It is not practical to cancel the sound over an extended area,
unless you emit the canceling sound at the same place that the
original sound is emitted.

Do u know whehter there exists such a product in the market and can be
bought through internet?

Thanks!

Loads of products (mainly military). Sennheiser PXC 250 - portable, foldable
noise-cancelling headphones are widely advertised at about $130.

Michael Kellett
[email protected] (anti spam - add 2 to use)

 

[Ron G]

Hi---

As an example, they are using noise cancelling mikes on the evening news.

Easy to spot, as they are two mikes about an inch and a half apart.

I helped design noise cancelling mikes. They work on the principle of sound
level pressure decreasing at the inverse square of the distance fom the
(source). Source distance is very, very important.

So, near a person's mouth, maybe 4 inches away, the (mouth) sound pressure
(differential) between two (evening news) mikes at 4 inches and 5.5 inches,
and pressure droppring at inverse square from the (source) is a somewhat
decent signal. This is what you hear.

On the news set, an errant noise on the set, say 10 feet away, acts
accordingly. The difference to the two mikes are 120 inches and 121.5
inches, pressure dropping at inverse square from the (source). This cancels
out, as the inputs are wired to oppose each other, and the sound pressure
level of the two signals are almost identical, and electronically cancel
out.

( a couple of hrs later-- a family problem has come up, this was sitting on
my computer, will post if anyone has questions---gotta go!)

Best--
Ron

 

[Ron G]

Anyhoo, if you use a noise cancelling mike, just run it into an amp and use
earphones---

Best--
Ron