Why Does My Phone Make My Radio Buzz?

When I first started dating my now husband, I went down to his house to watch a movie, set my phone down by his computer, and all of a sudden his speakers starting making an odd sound. (Sample audio on this website) While it's most common to hear that sound caused by a cell phone and affecting speakers, I also have a friend who was stumped as to why her bedside FM radio was static-y when she sat in bed with her laptop in her lap... unless she held her left hand up.

These are both examples of interference- though two different kinds. I'll be discussing the cell phone/speaker interference first. So what causes it? If you've ever heard it happen, you may have noticed that it happens right before the phone receives a call, text, or an email. This is because what you're hearing is the cell phone "talking" to the cell phone tower and vice versa. Little radio transmissions flying through the air to get to the phone are also being picked up by the speakers.

Not all speakers do this though. More and more speakers nowadays are coming with shielding that blocks out those kinds of signals, but if you have older speakers, or, in our case, speakers whose cables have been chewed on by a kitten, you may still hear it.

And the left-handed radio/laptop interference? From what I could get of the situation, it sounded like her laptop was picking up/sending out signals (my guess is that she had a device plugged into her computer that gets the Internet the same way a cell phone does), and when she had both hands on the laptop, her body was being a sort of antenna. While this is a bit freaky sounding, keep in mind that our bodies are mostly salt water, which is a great conductor. As soon as she picked up her left hand she wasn't as good of an antenna, and therefor the radio couldn't "hear" the interference.

Practical Tip of the Day:
While there's no good, easy way to shield a speaker you already have, there is a very easy, simple trick to stopping interference between a cell phone and speaker- move the phone! Bet you were expecting a complicated technical answer weren't you? Nope, sometimes the best way is the simplest way. Moving the phone away just a foot or two often fixes the issue.