can you hear your cell phone signal?

November 3, 2005 12:57 AM

some speakers, ive noticed, "chirp" when around cell phones. Car speakers, my old clock radio, and some large speakers in a lecture hall at my school all audibly click and buzz right before a cell phone begins to ring. Is anyone familiar with this phenomenon, and why would a speaker and cell phone signal interfere?
posted by Kifer85 to Technology (14 answers total)

I do. Clearly, you are not alone. It's electromagnetic interference.
posted by fourstar at 2:13 AM on November 3, 2005

Related and related.
posted by teleskiving at 2:43 AM on November 3, 2005

It happens in my classroom too. The subwoofer on the floor starts to buzz when a students phone is about to ring. (they are not supposed to have them on during school). It freaks some of them out when I hear the buzz and comment about someones phone is ringing and they need to shut it off. It has not failed yet.
posted by nimsey lou at 3:40 AM on November 3, 2005

It took me a month to figure this out after my job gave me a cell phone. Being a bit hard of hearing this was driving me nuts to no end.
posted by furtive at 3:58 AM on November 3, 2005

BTW, it's not the speaker picking up the noise, it's the amplifier picking up the noise and amplifying it.

This burned me once in perfomance. I was mixing for some band, and every so often, this horrid "duh duh duhhhhhh" would break into the mains. It was loud, annoying, and driving me nuts. I saw, and heard, *nothing* on the inputs or on my sends.

Finally, "duh duh duuuuuuuuudhdhdhddhdhd RING" -- and the bass player sheeplishly grabs his cellphone -- off the rack on the side of the stage where the main amps are.

Yeah, digital cellophones make noise. That "duh duh duuhhh" is basically a quick sync with the cell tower. If you want to hear the full sync, put the cellphone near a set of powered speakers and call it.
posted by eriko at 4:46 AM on November 3, 2005

At my previous job, a co-worker in the cube next to me would say, "Oh, I'm getting a phone call" several seconds before it rang. Creeped me out until I learned how he could tell (chirping noise over his PC speakers, consistent with eriko's description), and even then it was a little weird.

This phenomenon has shown up in some automobiles, too. Technicians start replacing parts in a vain attempt to fix it.
posted by pmurray63 at 7:46 AM on November 3, 2005

Right before I'm about to get a phone call my computer monitor gets all fuzzy.
posted by TurkishGolds at 8:04 AM on November 3, 2005

Same thing happens to me. Now, every time I hear my computer's speakers buzzing, I immediately grab for my phone. If my cell is close enough to my speakerphone, the speakersphone will also start to buzz.
posted by apple scruff at 8:14 AM on November 3, 2005

It will do the same one a telephone (i.e. landline) which you - or someone else - is using, if a cellphone is about to go off nearby (or receives a text message).
posted by Chunder at 8:26 AM on November 3, 2005

I rememeber doing this once in my car ... I heard the "Dit dah dah dah dit dit dit dit" and grabbed my cell phone, positioned my finger on the green button ... and then it rang. My boss, riding in the passenger seat, was impressed. (and a little spooked.)
posted by SpecialK at 9:27 AM on November 3, 2005

Yeah, digital cellophones make noise. That "duh duh duuhhh" is basically a quick sync with the cell tower. If you want to hear the full sync, put the cellphone near a set of powered speakers and call it.

I tried this with my PC speakers, with no results. I must be missing something here, right?
posted by jimmy at 10:51 AM on November 3, 2005

Your PC speakers are probably shielded, jimmy?
posted by nobody at 11:39 AM on November 3, 2005

My old nokia phone did this in my car, and it was always very loud and annoying, but my new motorolla doesnt : )
posted by nile_red at 11:44 AM on November 3, 2005

Yeah half the speakers in my house do this. It would be interesting to make some sort of device that capitalized on this principle, maybe detecting a switched on cell phone in a theatre, or just to buzz in your pocket to give you psychic phone sense to impress your friends.
posted by shanevsevil at 1:21 PM on November 5, 2005