destructive noise generation to cancel noise from machinery

So thanks to the helpful advice from members in another forum area I now have this

http://www.youtube.com/watch?v=QFnbfUVI0ro

Only problem with pneumatics is the noisy compressor. I know there are a few threads on noise cancellation, but would it actually be possible to make a setup that could cancel the sound made by the compressor? Is that even possible?

Idealy, something that could listen for a repetitive sound and then produce a sound to cancel it.

Alternatively I could build a box around the compressor and suck out the air, with only a tube running to the compressor air inlet. But the first method would be way cooler.

Thanks for the help,

Van

Dude, that sounds is actually the coolest part of the project. Don't you dare try and eliminate it. :D

EDIT: So say I was passed out drunk and sleeping it off behind your door (just sayin), would it kill me?

Lefty

Noise cancelling headsets do just that. For open space, now you are cancelling sound but more or less in specific sweets spots where your microphone is and where your speakers are pointed at.

So technically possible, just not with an arduino.

Bose headsets can do that at $300.

Would it be within the realm of possibility to have the arduino record a few seconds of sound, calculate the inverse sound wave, and then reproduce the sound through speakers?

If that's not possible, how about record samples of the compressor playing, and then somehow create a sound file that would cancel it out? Can the arduino play sound samples? I would think that the sound the compressor makes will be consistent through its entire life.

I really have no idea though, I'd research it more thoroughly but I've got to finish the report on my door opener lol, doing a presentation on it tomorow -_-

Edit 1: @Lefty: the cylinder generates barely enough pressure to open the door, I don't think there's much risk of bodily harm.

Actually the sound you hear is most likely not the air compressor but rather just the air cylinder exhausting/venting the air when commanded to close, with an internal spring supply the motive force. What some do is screw on a small 'muffler' component to the venting port of the air cylinder, it might quite it down enough for you not to mind it, but at the expense of slowing the closing action even more.

All this electronic talk of noise cancelling is pie in the sky, too many beers to fear ideas. You can't afford it and a Arduino can't do it.

But I will still go on record that the sound that makes in your demo is the coolest part of the whole demo. Why change it?

Lefty

O I agree, that's the sound of the solenoid venting. I've been sitting here for an hour just listening to the sound over and over and haven't gotten tired of it.

I was talking about the air tank compressor, I can get maybe 50 cycles before the compressor kicks in to top up the tank, and its pretty loud.

Just put lots of foam around the compressor, and/or use a large air reservoir so it rarely has to run. You could add a really large reservoir and only allow the arduino to 'charge' it at certain times of day unless absolutely necessary, too. What kind of compressor are you using? It really shouldn't have too be very large.