Ask HN: Why do my speakers make a weird noise near a phone? | Hacker News Reader

Ask HN: Why do my speakers make a weird noise near a phone?

11 pointsdsc15 comments

What does this represent?

It usually starts when someone is about to call. But sometimes it goes off and no one's calling(that's scaring me).

It's electromagnetic radiation from your phone. When you're about to be called, it will pick up the call request from the cell station and answer the request. The EM radiation from the phone induces a current in nearby cables, which is transformed to sonic waves by the speakers.

Hmm I'm kinda concerned that someone might be spying on me :)

But yes, I saw both your comments and "sometimes it does it for no reason" is still scary to me.

Could be your phone being pinged in order to keep tabs on your location. I would throw the phone away and change your identity. You must have upset someone in the government.

That or its nothing at all.

It's just pinging the nearest base station in response to a periodic poll of which devices are in the cell, like a 'stay alive' ping on a temporarily dormant FTP session. You can probably limit how diligently the phone keeps in touch with the network but will have more missed/dropped calls as a result.

Well, the only way to make 100% sure you're not spied on with your mobile phone is to turn it off AND remove the battery. I recommend this method for the paranoid moments in your life! ;-)

That is the "GSM noise" (http://www.corporatetalkradio.com/thatnoise.html).

Slightly OT: One of my favorite easter eggs in Grand Theft Auto IV is that the GSM noise plays just before the in-game cell phone rings. That really had me confused for a second.

Ages ago, I had a Nokia phone with a now defunct U.S. provider called Voicestream. I could hear the callers talking before I picked the phone. Sometimes I would hear "He is not answering", but in a few occasions, I heard horrible things :-)

I don't even know how that's technically possible. I held on to long after the handset was out of fashion.

Oops, I forgot: Sometimes your phone will make contact with the cell network for no apparent reason. Don't be scared! =)

What type of phone and what brand / model of speakers? The iPhone is kinda known for doing this to speakers.

[edit] http://www.iphonematters.com/article/speaker_interference_th...

I have heard you can remove that noise by putting magnetic snap things over the power line of the speakers you have. It looks like a capsule that opens halfway and then you snap the cord in between. I have a ton from old plasma/lcd installs as most people just throw them away in the box.

I've owned some Sony Ericsson models (the old T610 comes to mind) that were actually well shielded and wouldn't cause any audible interference with speakers.

Sorry, but that just doesn't make much sense. The phone "wants" that radiation to go out, since it uses it to "speak" to the cell network. Shielding that radiation would be like gagging yourself and then trying to talk to someone... What makes a difference to the audible sound are mostly carrier frequency, pulse frequency and, yes, field strength (but you still wouldn't want to suppress that by shielding it).

Whatever the case, that phone never caused any audible signals in my speakers :)

Yeah..this also happens with my phone. Usually just about 5 secs before a call or SMS is received.

Cdma phones don't do this.

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