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I actually want to amplify and enhance the cell phone interference you often hear when speaker setups are un-shielded. I wondered if I could reverse tactics people are using to get rid of it? The idea is to have an art project where the sound is actually everyone's phone checking in and receiving texts and such in real time. Thanks!

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Are you looking to reproduce it yourself or do you just want a recording of it? I do believe I have a recording of it somewhere...

Also, which kind of interference are you looking for? CDMA makes a different interference sound than the IDEN network that Sprint / Nextel Network.

CDMA makes that "beep bepbepbep bepbepbep bepbepbep" sound, where IDEN makes more of a "Ffftt ffftt ffftt" sound. (please excuse my attempts at onomatopoeia).

I have found that lav mics tend to be extremely sensitive to the interference. So, theoretically, if you wrapped a lav around a phone a few times, then connected the phone to a call (obviously one that wasn't making any noise! Perhaps try putting the call on hold...), then leave the phone in a silent room. You would probably get a decent amount of RF noise.

  • i am trying to pick up both as much as possible. This will be a public event with numerous people (and thus phones( in the space and I want to make the constant data transmissions and cell tower check-in audible. At my old university the PA system actually picked up so much of this that all phones had to be powered down during speaking events. – digitalColeman Mar 27 '11 at 0:43
  • @digitalColeman Hmmm. You may have to go with faking it. Either that, or run a TON of unbalanced cable everywhere around the room (probably a few thousand feet, I'd imagine...). It basically turns into a giant antenna. Might be worth trying out. – Colin Hart Mar 27 '11 at 3:34
  • I discovered this weekend that a 3G phone that downgrades to EDGE - like the iPhone 4 - will still make the CDMA interference noise when it's running on an EDGE, non-3G network. "Sorry, boss, I need to drive to the edge of town to use my phone to get this effect! Really!" – NoiseJockey Mar 28 '11 at 2:09
  • @noisejockey -THAT'S what the E stands for! EDGE! I've been wondering about that for two years. – g.a.harry Jul 30 '11 at 10:47
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Look for the plug-in called Speakerphone. It give you independent controls over all aspects of many many different kinds of speakers, including cell phones. Thea controls range from distortion to radio interference complete with EQs and more. It's really a must have.

I believe by using some of the radio interference controls (automated to move around the graph) within the cell phone speaker preset, you could achieve your desired result

  • hmm, that is a good fallback, but I would really like to use the actual noise we are always getting accidentally and amplify it. For instance I didn't know if hanging some of the speaker cable in coils or stringing it around the space might work to pick up more of the noise. Thanks! – digitalColeman Mar 26 '11 at 20:48
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Maybe you could try using induction coil mics. You can get these cheaply, I got mine at Radioshack for 8 bucks. Not sure how easily they are made.

http://www.radioshack.com/product/index.jsp?productId=2103876

As an example of what can be done with that I made short recordings using the signals emitted from an external hard drive, digital camera, and an iPhone.

http://www.youtube.com/watch?v=FBBW6Ol7AfY

http://soundcloud.com/sigimueller/i_duc-improv

Maybe this will get you closer to what you are looking for?

  • +1. I got great signal to noise ratio using an induction coil mic, also from Radio Shack, to record that dit-dit-dit interference from my iPhone while on a 3G network in the countryside. – NoiseJockey Jul 29 '11 at 4:28
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The other day, i was worldising some stuff through my iphone. I kept getting that interference when the mic was too close, so i had to back it off a few feet before it disappeared. I'd guess that you could get the interference pretty well in a quiet environment if you set your phone to silent/vibrate off; put the mic pretty close; and then sent it texts/called it.

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I have a spare guitar pickup for grabbing sounds like this.

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going back to the original question:

The idea is to have an art project where the sound is actually everyone's phone checking in and receiving texts and such in real time.

You could explore using a very long wire as a dynamic/coil pickup then hook that up to a sufficiently quiet preamp (no phantom power!), then find a way to place that above people's heads or just in very close proximity (wall, floor, etc). This may or may not work, and consider trying it with the cheapest equipment possible first. In theory any long unbalanced wire (even line in) should pick up cellphone interference easily.

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I often caught that noise while recording with Zoom H4n and not turning off my cellfone.

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I always thought that noise was induced into the speaker itself. I used to get it like crazy until I sold my speakers - long story - even though I always run balanced cable.

I would investigate where exactly the noise comes from and ends up. Try a powered monitor with the power on, but the xlr unplugged. Then try a regular car stereo speaker. Then just bare xlr and unbalanced cable.

I suspect that the noise is actually both induced and amplified in the mini power amps in your monitors, so that may be a way to set up your installation without having to use any cable at all. Having an array of like 45 speakers would also be really cool to walk into.

One thing I noticed is that it's pretty bad when transferring data, but SMS makes it go cuhrazeee. You should ask people to write down their contact info so you can text 'em while they're in the room to make sure you get the bdst effect.

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