Comments on: Why does my computer make noise when my cell phone rings?

Question: Why does my computer make noise when my cell phone rings?

Specklet — Tue, 04 Jan 2005 11:11:56 -0800

Does anyone have a theory as to why my computer might make little rhythmic noises for a few moments when, (a) my cell phone is at a minimum 12" near it, and (b) my cell phone is receiving an incoming call? It also does it when I receive or send text messages...

By: Faint of Butt

Faint of Butt — Tue, 04 Jan 2005 11:16:03 -0800

I don't know why this happens, but when I worked as a relay operator we would hear little clicking rhythms in our headsets whenever someone on the floor sent a text message from his or her cell. It's probably the same phenomenon.

By: skwm

skwm — Tue, 04 Jan 2005 11:17:24 -0800

That would be Maxwell's Theory

By: Specklet

Specklet — Tue, 04 Jan 2005 11:22:40 -0800

Yeah, I'm familiar with Maxwell's Theory, but what in the housing is making the noise?

By: Ufez Jones

Ufez Jones — Tue, 04 Jan 2005 11:27:56 -0800

See here for some info. This happens to me when my cell is by my alarm clock as well. Even stranger, I heard it come from a police louspeaker yesterday when someone was standing by a squadcar. Kind of freaked a lot of people out.

By: MrZero

MrZero — Tue, 04 Jan 2005 11:34:43 -0800

Perhaps it is similar to the noise discussed here?

By: Wolfdog

Wolfdog — Tue, 04 Jan 2005 12:01:06 -0800

Turn down your speakers and see if it goes away -- my guess is that's where it's coming from. If all the wires and bits in the audio system aren't well-shielded, you'll hear EM disturbances through the speakers.

If you think it's something mechanical, actually moving, I don't know.

By: sonofsamiam

sonofsamiam — Tue, 04 Jan 2005 12:55:41 -0800

Whenever a cell call comes in while my band is practicing, you'll hear a rhythmic clicking or buzzing over the amps, sort of like what an old-skool computer game sound effect of a pony's trot might sound like.

By: Specklet

Specklet — Tue, 04 Jan 2005 13:06:36 -0800

Thanks for the suggestions, guys, but here's the weird thing: I don't have speakers.

By: bobo123

bobo123 — Tue, 04 Jan 2005 13:15:22 -0800

Thanks for the suggestions, guys, but here's the weird thing: I don't have speakers.

Are you sure? Most PCs have a speaker in the back that makes a "beep" sound on boot up. They can be quite loud but were only ever really used by really old DOS games.

By: Specklet

Specklet — Tue, 04 Jan 2005 13:41:29 -0800

Most PCs have a speaker in the back that makes a "beep" sound on boot up.

D'oh! Of course I have that! Foolish Specklet.

And I swear, this machine dates from the time of DOS games. O woe, why can't I work from home!

By: Dipsomaniac

Dipsomaniac — Tue, 04 Jan 2005 13:53:33 -0800

My cell does this as well when it's on my desk near the speakers. What you have is a crude aerial in there and it's picking up transmissions to and from your phone. My phone is GSM so sometimes I hear it when the phone is updating the time over the network, and I get about two seconds warning when it's going to ring - I hear the chatter before the ringer sounds.

By: Doohickie

Doohickie — Tue, 04 Jan 2005 14:37:33 -0800

I get the same thing on my car stereo if my phone is in the cubby hole below it and rings.

By: Faint of Butt

Faint of Butt — Tue, 04 Jan 2005 15:50:45 -0800

sonofsamiam's "trotting" analogy is extremely apt. It was a funky little "ti-pi-ti, ti-pi-ti" beat. You could dance to it, if you wanted to (we needed entertainment at relay). I never realized this was so universal.

By: Specklet

Specklet — Tue, 04 Jan 2005 16:19:28 -0800

Yeah, the old-skool digital trot is exactly what it sounds like...

By: seanyboy

seanyboy — Tue, 04 Jan 2005 16:19:45 -0800

I wonder if there's a difference in how mobile phones are shielded in different countries. Here in the UK, it's a well known phenomona. So much so, that if you're on a land line and that distinctive buzz sounds, the person on the other end will (sometimes) ask you if you want to get the other call.

My guess is that it's simply interference caused by having quite a powerful radio transmitter near wires connected to speakers. The radio waves cause induction cause the noise.

Some info here.

By: oaf

oaf — Tue, 04 Jan 2005 20:21:56 -0800

I never realized this was so universal.

Yeah, the really bizarre thing is that it is the same for TDMA and GSM phones.

By: MotorNeuron

MotorNeuron — Tue, 04 Jan 2005 21:39:45 -0800

It may be the spirit voices in your coffee maker.

By: tracicle

tracicle — Tue, 04 Jan 2005 22:39:51 -0800

There used to be an ad on the radio that made that noise on purpose, I guess as an attention-getter. Drove me nuts. It really is a sound that most people recognise these days. My car stereo is the worst, mainly because that's the only amplified source that I put my phone near. My sister manages to always put her phone on our stereo at home and it freaks her out every damn time.

Apparently it shouldn't work without some form of amplifier, which those little midi speakers don't have (according to my geek hubby). Specklet, you don't have built-in speakers in your monitor?

By: azazello

azazello — Wed, 05 Jan 2005 02:08:38 -0800

This post explains it pretty well.

It's ubiquitous and pretty annoying - put a phone near a fairly long unshielded low-power audio line (i.e., antenna) connected to any kind of amplifying circuit and you can be fairly sure the speaker at the end of it will emit this pulsing noise when the phone is conducting any traffic with the cell in high-power mode. Even my Thinkpad, which is as shielded as can sanely be (most of the PCBs inside are protected by 3 or more layers of metal) receives this, apparently because of the unshielded parts leading to the audio jacks.

The only solution is to either move the phone further away or buy a better-shielded component. Or cut the wires from the speaker in question :)

By: azazello

azazello — Wed, 05 Jan 2005 02:13:25 -0800

For what it's worth, oaf, I never heard that interference from my old TDMA phone. On the other hand, GSM and TDMA are very similar in terms of the transmission protocol (GSM is built upon TDMA as far as I know).