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Is it be possible to set up noise-cancelling speakers to create silence at a certain position?

Is it possible to position a pair of speakers in such a way that they create a bubble of silence?

Say you were to play a sound through one speaker whilst playing its inverse through the other. If you were to place your head at a very exact point between them, would the sound disappear?

I am interested to know if this is possible in theory but also if it would be feasible for layman to do.

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Vyger2 years ago

yes, it is a technology that has been in use for some time now. You will however never achieve total silence since sound comes from all directions but you can eliminate certain frequencies. There is a hydro electric dam close to where I live and they use sound canceling technology to eliminate the noise in the main generator area. It used to be that hearing protection was mandatory for anyone to enter the area because the noise was so loud. Now when you walk in you can hear some noise but not much. You can have conversations in a normal voice. But you can feel the tremendous vibrations going on as the water pushes the giant turbines. If you put your ear to the railing you can hear it but in the room itself its quiet.

They have also experimented using noise canceling in high end refrigerators. In the area of the compressor they put a speaker that makes noise opposite the compressor noise. The result is a very quiet refrigerator.

By the way, you don't have to be at the exact center. Frequency cancellation occurs everywhere where the 2 waves meet which is why it can work for an entire room.

There is a lot more about it on line. Do a Google search/

King.Rawrawr.the.first (author)  Vyger2 years ago

I did some googling before asking, but didn't come up with an answer to my specific question - at least, not one which enabled me to do what I'm attempting.

Ideally, what I would like to do is have a pre-recorded track, playing it through one speaker whilst playing an inverted version through the other. I was hoping it would be possible to set it up so that people could hear the track unless they were standing at the point at which the two cancelled each other out.

I have been trying to do this using white noise, but I can't tell if I am actually creating a quiet point.

To understand it better remember that sound is a wave. Waves can cancel each other out yes, but they don't eliminate each other. In fact waves go through each other and continue on. If you make a wave at one end of a pool and an identical wave at the other end at the same time the 2 waves will meet in the middle, add together to make one twice their size at the meeting point, and then continue in the direction they were going in. They pass through each other. Everywhere that the sound waves meet they will cancel each other out, but that will not just be in one spot. It will happen everywhere in between the speakers and continuing on bouncing off the walls and coming back. This is why sound cancellation works for a room and not just a few points in the room. If you made only one instant of sound, one pulse of a speaker, then initially it would cancel out at only one point, but then the sound reflecting back from the wall would be there again, an echo as it were. traveling at the speed of sound. Your idea might work with resonating frequencies, but it would be very difficult to figure out especially in 3D with angular walls.

rickharris2 years ago

Yes I have a very nice pair of JCV noise cancelling head phones - They work well with constant noise such as a car or aeroplane. but don't cancell speech.

iceng2 years ago

There is a company that makes transducers that cancel car road noise by placing two or four in the car ceiling .

Search New York, NY.