Why does my computer speakers make weird noises when my cell phone rings?

Question

Usually in the day, when I'm on the computer, and my cell phone rings, my speakers make some weird noises. But the weird thing is that when im sleeping at night with my cell phone and speakers off, it still makes the noise! what is this?

Answer 1

This happened to me too... maybe not that specific example, but even when my speakers were off they would pick up phone calls and radio station signals. I remember I caught some of my brother's phone conversation one time, and a broadcasted worship another time.

I still am not 100% sure why it did it, but I'm guessing that they're on the same frequency. There's nothing you can really do to stop it short of keeping your cell phone away from the speakers. Mine stopped, but I don't know why. I think we might have gotten a different phone or something.

So basically, my most-likely-flawed theory is that they are on the same frequency and the cell phone messes up the speaker's signal, even when it's off. That answer's probably entirely wrong, though.

EDIT

The guy above me (Gary) totally showed me wrong. His answer seems... right, I guess. Too bad he answered while I was writing mine.

Answer 2

You probably have a GSM phone (AT&T or T-Mobile in the USA, pretty much any phone in Europe and much of asia). This is pretty common with this kind of phone.

Here's the deal -- when it's active (responding to the cell tower during a "ring", sending your voice, etc) the phone is transmitting, as you would expect. This is not continuous transmitting, though, but sent in packets, roughly 150-200 times per second.

So that radio signal is happily picked up by all kinds of different electronics, and usually ignored.. it's either at 850MHz or 1900MHz, way too high a frequency to hear, or even affect many things. However, what you hear in the speaker is that 150-200 cycle on/off from the GSM phone's transmitter. And since the energy comes from your cellphone, not your stereo system, it's quite possible that lower power speakers will respond all by themselves... a GSM phone can output up to 2 watts of radio frequency power.

If you shut your cell phone completely off, you won't get this. However, watch out -- some cell phones don't actually go completely off when you think they're off... they may still be responding to the network and just muting the ringer.

Aside from switching to a CDMA phone (Verizon, Sprint), you can do a few things. If the phone isn't totally shut off when you turn it "off", pull the battery out. If that doesn't stop this, it's not your phone doing this at night, but someone else's.

If you have speakers that are separate from the stereo (as in a component or bookshelf stereo system), you may be able to help prevent the high frequency signal from going into your speakers, particularly if it's getting in by way of the speaker cable. Get yourself a couple ferrite rings (that bump you sometimes find in USB or keyboard cables) and run the speaker cable through it once or twice, near as possible to the speaker. If the speaker itself is shielded, this can prevent the RF from getting there.

Also, keep your cellphone as far as possible from the speakers and any speaker wire. The power of an omnidirectional RF signal from something like a cellphone drops off with the square of the distance from the source... so if you move your phone from 3ft to 6ft from the speakers, the energy getting to the speakers will drop by 3/4.  

Answer 3

your speakers work using electromagnets to vibrate a material making a sound and your phone uses electromagnet signals to transmit information so the electromagnet in the speakers picks this up wether they are off or not, and it does it when your phone is switched off because data is still being transmitted to your phone this is always going on unless there is absolutely no power to your phone

hope this helped

from

gary

Answer 4

your computer signal interferes with your phone signal.  Its no big deal