Is it possible to cancel out sound using hi-fi speakers?

I know that noise cancelling headphones exit but is it possible to scale that up and have the out-of-phase noise played through speakers? 
If so, and the microphones were against the wall of the offending neighbour and the speakers were to be aimed at that wall, would the noise be noticeably reduced?


Thank you.



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Unfortunately, no.

The reason it works in headphones is due to the fact that when a speaker is against your ear, you eliminate many variables with regards to the behavior of sound.  The elements of the microphone and speaker have a predictable response and is positioned in the exact spot where sound enters the ear canal.  Room acoustics are not a factor because the cup of the headphone attenuates most of this.  All that is really required is that the signal from the microphone is reproduced 180 degrees out of phase and time-aligned with the point where the sound enters the ear, and for that headphones work beautifully.

In your scenario, the vibrations caused by the offending neighbors are traveling through a wall that, depending on construction (materials used for the wall, depth and width of studs, type of insulation, and even the type of paint) can vary wildly.  The position of the source of noise can vary as the neighbor can stand anywhere on the other side of the wall, and that will vary how the sound interacts with the wall.  Once the sound emerges through the wall, it will have a different pattern of propagation than what the hi-fi speaker would, and the room acoustics will alter the sound of both the noise and the hi-fi rig in unpredictable ways.

Even if you were able to dial in cancellation of certain frequencies at one spot in the room, if the listener or sound source moves then the effect is destroyed.

The only way to actually cancel the noise in this scenario would be to make the wall vibrate as a speaker, exactly countering the vibration of the sound source.  This would require that the entire wall would have to sense the vibrations coming from next door and match each node of vibration at every position to counter it.

Believe me, if this were possible I'd be a happy man - it would be a breakthrough in acoustical engineering and design, making traditional means of soundproofing for studios obsolete.  The cost might be about the same, but at least it wouldn't require building rooms within rooms and the exotic methods of mechanical isolation of the walls and floor from the building.

Would this still happen if there was no wall? Lets say the sound came from the same room as the system and you were in. Also how effective would it be for loud and quiet sounds if it worked?

AbinA21 year ago

hi

i wanted to know if its possible to active noise cancel the monotonous sounds like sound of a hair dryer

is a type of white noise, but in theory shift by 180 degrees and with fast enough sampling it is possible (theoretically)

dilyusha1 year ago

Hi, maybe a little out of the title but does a vibration speaker glued to the window would make a flat full size cancelling system? Only question is the circuit and what type of mic to use.

SteveP82 years ago
Burf7 years ago
The following is a quote from from a website I found HERE.

"One cool idea is to suppress unwanted noise from another apartment by vibrating your wall out of phase with the sound from next door.

For example, suppose the person in the next apartment has his stereo on real loud. In some cases, you can even feel the wall vibrate. By placing devices on the wall, you can detect the wall vibrations and generate vibrations in an opposite phase. Thus would completely cancel out the noise coming from the other apartment.

Although there are some new devices available that use your walls as a speaker by creating vibrations, it has not yet been combined with detectors and noise reduction electronics. This is an invention that is begging to be developed.
"
IsaacS6 Burf2 years ago

this method is used on helicopters to cancel out the crazy vibrations the engine and rotor blades induce into the helicopter fuselage

What I wonder and this is a primitive idea and would evolve over years and millions of dollars. But could you just do the thing they are working on where you turn your walls into speakers, then just pump white noise like a mountain stream or rain. Using Bone headphone technology would seem to be a good start. It would be generic damping. Might get 17%. It would be like an electronic curtain so to speak. Because having a microphone to detect the sounds and phase them out would be the next step from this, Billions for that.. Rome was not built in a day. We have to start somewhere. But I think building soundproof in will always be the best way, unless you could develop flat plates. don't think you could suction cup them on. You'd have to bolt them on to the studs so make them large enough to be able to attach on 2 studs.

anarnold3 years ago

Consider Damping. Basically the final cause of the noise originating next-door making into in your room is the wall-board facing your room vibrating. You could try bookshelves against the wall-I've found tightly packed books to be excellent sound absorbers. There are also self-adhesive asphalt damping sheets but they are expensive.

A devilishly clever thing to do would be to put in false half-wall built with drywall framed onto 1.5" furring strips. the wall would essentially "float"; not being connected to the real wall behind it. You would lose 2" of floor space along that wall, but if there's molding and baseboards, it would be totally undetectable.

For added damping you could fill the false wall with ziplok bags filled with play sand.

bobzjr5 years ago
It sounds (no pun intended) like Woody Norris is doing some work which might be able to do just what you are asking. This guy is amazing.
See his homepage at http://www.woodynorris.com/

Really good stuff here, including video... http://www.ted.com/speakers/woody_norris.html

In part of the video, he talks about the real possibility of silencing snore sounds while in bed. My wife would REALLY like this one.

Picture below is Woody.
Woody Norris.jpg
FriendOfHumanity (author)  bobzjr5 years ago
Thanks for the link.
What an interesting chap.
lemonie7 years ago
You might do better placing your speakers up against the wall and pumping loud music to the neighbour. Bat-out-of-hell on repeat and get out of the house for the afternoon....

L
Jayefuu lemonie7 years ago
Barbie Girl by Aqua would be much more annoying since bat out of hell is a good song.
lemonie Jayefuu7 years ago
BOH is only good for so many plays, then it starts getting annoying (it happened to me, which is why I thought of it...)

L
Re-design7 years ago
It would be easier to just crank up the volume of your set to mask the interfering sounds.

A Japanese appliance mfg. did release a line of  appliances that used off phase sound to mask/eliminate the sounds of the working.  It was somewhat successful but they have since stopped mfg. of the hardeware.
      Probably not.  Check the theory of noise cancellation.  It is hard for a microphone to detect a sound, and then have a circuit send its "reverse" (180 deg. out of phase) out speakers.  It doesn't even work for music through noise-cancelling earphones.   

      How about aversive conditioning for the neighbor?  You make a high-pitched squeal circuit, tape the output  to the wall, have the neighbor's loud noise control it.   The neighbor will wonder why loud music makes him/her uncomfortable, and hopefully turn it down.  Maybe a low thudding frequency would work too.

    I'm sure one of the clever Instructable readers can come up with a circuit to do that.  The microphone circuit would have to be insensitive to the output frequency.