Plug-In Noise Cancelling - Does this exist?

".jdb." (brockmjd) 01/14/2015 at 10:08 • Filed to: None

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My hearing is crap. I know this, it stinks, whatever, I deal with it.
Sometimes, though, it's a pain - like when my kids are in the backseat of the minivan and I can't hear them over the road noise.

I know that noise cancellation technology isn't particularly complicated - you need a mic, a processor to create the cancelling signal, and a speaker. ANC headphones work great. And I know that some cars build ANC into the stereo. But since I don't have that.... this would be awesome: An ANC system that I could plug in to the car's aux port. Plug it in, turn the stereo to aux, and constant-frequency noises (like wind and road noise) are greatly reduced. Obviously, I couldn't listen to the stereo while it was on, but we don't listen to music that much in the car.

Does this exist? It seems like it would be useful. Google wasn't much help.

McMike > .jdb. 01/14/2015 at 10:12

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I have a hard time with certain frequencies. My brother-in-law's voice is a great example. We could be in a loud place (bar/restaurant) and I will hear everyone else but him.

I'm very conscious of it. I'll pay attention to his volume, and compare it with everybody else's, and I'm convinced it's his voice. It's weird.

I also try this with my wife every time she says, "Were you not listening to me?" but she doesn't buy it.

yamahog > .jdb. 01/14/2015 at 10:14

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Get them some megaphones, what could go wrong?

macanamera > .jdb. 01/14/2015 at 10:18

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This is is actually a really interesting idea...and I'm not sure it exists. Let's bring it to market.

.jdb. > yamahog 01/14/2015 at 10:21

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.jdb. > .jdb. 01/14/2015 at 10:23

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Replying to myself - I think that this could be something where a Raspberry Pi would work really, really well. Power comes in from 12v DC from the cigarette lighter; sound goes out from an aux port. All you'd need is a mic and linux-based software to create the noise cancelling sound and...theoretically, that should be it.

macanamera > .jdb. 01/14/2015 at 10:24

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Let's do this man!

jariten1781 > .jdb. 01/14/2015 at 10:26

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It'd be easier to just put a mic in the back of the car and a speaker near you. When I was a kid we had some cheapo Fisher-Price walkie talkies to talk to the parents from the third row of the suburban on road trips. That sucker was loud. My dad would also use CB or military speak so it was cool, like we were in a war zone or whatever (well, while we were less than 10...after that it was groan inducing, which I'm sure he found hilarious).

CalzoneGolem > .jdb. 01/14/2015 at 10:34

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How about some additional stick on sound cancelling?

Too low tech?

Grindintosecond > .jdb. 01/14/2015 at 10:38

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The only problem with this idea is the actual audio capability of the car stereo, not so much the ability to produce the sound, but the ability to produce the sound in enough volume....and i dont mean turning up the volume. Can the speakers move the necessary amount of air to produce the effect car-wide. I'm sure a cost effective purchase from Crutchfield will fix any of those problems.

If you want to pursue this idea as an actual solution, go rip an active cabin system out of a equinox. They use it to hide the engine vibrations from running cruise speeds below 1500rpm. if you want something else and possibly go pitch the idea to a company, contact the Ultra Electronics guys. they build the systems installed in the aircraft cabins of turboprop planes.

DrJohannVegas > .jdb. 01/14/2015 at 10:38

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I concur that this sounds like a really cool idea. But, a couple of ideas for why it's tough in a car. (Not that these problems haven't been overcome: see the Bose system.)

1) Generating an accurate inverse waveform requires some real computing. Not something you are gonna get in a small, simple device. (Although, maybe a Pi could do it.) You need something that can process audio and do it really quickly, because:

2) Active feedback like this is really sensitive to latency. The longer the gap between the sound and the response from the system, the worse it's gonna be. (I can imagine it's possible to have the software sample the result and then adjust if the constant noise remains, but retain the previous waveform output if it's quiet. I dunno. Anyway, the slower the system, the more it become "more noise")

3) Bose already has some patents on this, and sells to the automotive market. So, you'd have to find a way to get around them with your design.

That said: http://www.digitaltrends.com/cars/harman-wa… Folks are workin on it.

As for hearing the kids over the road noise, maybe rig up a small mic (or pair of mics) to a tiny pre-amp, then run that into the stereo with the fader all-front? Kinda like a megaphone, I guess, but sometimes it's easier to amplify the signal than reduce the noise.

The Real Dacia Sandero > .jdb. 01/14/2015 at 10:40

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Noise cancellation isn't quite as simple as just getting a mic to listen for noise and then playing a sound. To explain the mechanics behind it is difficult, but essentially, it has to be tuned for the acoustics and where the listener is in the space. Headphones work, because they are always in the same position on your head. Car audio systems range from awesome to horrible, and different sets of speakers would affect how all that works. The wikipedia article explains a little better what I'm talking about.

http://en.wikipedia.org/wiki/Active_no…

While it's possible to do this(as cars have it and whatnot), it would be nearly impossible to make a device that would work well in every vehicle without being big money. Also, the general opinion I've heard of most in vehicle noise reduction systems hasn't been that positive.

Source: I'm an audio engineer with a basic understanding of frequencies and the mechanics behind sound cancellation.

GTI Sprinks > .jdb. 01/14/2015 at 10:43

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What about adding noise-dampening materials. Not sure of your technical abilities, but removing door cards, headliner, trunkliner, etc and adding noise-dampening material would cut down on road-noise.
Familiar question seen here: http://www.instructables.com/community/Acti…

Also to consider: tire selection can have a huge effect on road noise.

It's a question that's been asked often, but only as of late coming to more interest. Bose just started offering this idea to OEM folks, i can't imagine a stand alone head unit is too far behind.

.jdb. > DrJohannVegas 01/14/2015 at 10:46

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Yeah, I did some googling after my post and started to see the problems - it seems like the biggest are that the Pi would have some latency (which you could theoretically code for, as long as it was a constant waveform you were trying to cancel) and that ANC headphones are feasible and cheap(ish) because you're trying to cancel sounds in a very small area (your ear) with a speaker that's RIGHT THERE..... Trying to get 180 degree out-of-phase sound from 8 speakers to hit you perfectly....probably not so easy ;)

I think the next-best thing is going to be to get some ANC headphones and remove all the passive noise canceling stuff that I can — i.e. cut away anything that "seals out" outside noise.

WRXerFish - WRX-Wing pilot > .jdb. 01/14/2015 at 10:47

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There should be a small intercom system that can be installed in the vehicle.

DrJohannVegas > .jdb. 01/14/2015 at 10:52

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Yea, it's tricky stuff. You might get some benefit from passive noise cancelling in the car. Sound deadening material on the floor, maybe taping over gaps in the bodywork. Sounds crazy, but it can make a difference at highway speed, and you may not need cathedral silence to get what you want.

Or, you know, give the kids megaphones.

deekster_caddy > .jdb. 01/14/2015 at 11:05

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Just put on a set of ANC headphones and don't play any music through them. The rest of the drones should be cancelled out, but you should still hear the important things like voices and sirens and such, even your music being played through the car speakers (although it will be damped).

Textured Soy Protein > .jdb. 01/14/2015 at 11:11

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Plug this into your aux jack.

Added benefit of you can get some sweet THRESH DECAY when you're shredding on the guitar.

Wrong Wheel Drive (41%) > .jdb. 01/14/2015 at 13:41

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That seems like a really interesting project, but I really doubt a simple plug-and-play solution exists or could be created. The cost of making this feasible would be enormous! Passive noise canceling would really be the best solution or perhaps passive sound amplification could work too. By this I mean building something that could amplify sound such as voices coming from the back. Kinda like how this thing works http://www.houdsound.com/passive.html . Or using concave reflectors like this: http://www.physics.umd.edu/deptinfo/facil…

If only EssExTee could be so grossly incandescent > .jdb. 01/14/2015 at 14:41

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I'd rather cancel out the kids and only hear road noise.