What causes the interference on this phone's 3.5mm?

Question

I plugged my LG G2 into my mixing desk yesterday to listen to some music through my system and I discovered the strangest of interferences coming through the speakers. I hooked it up to my recorder, filmed the screen and synced the two together. You can see it here:

I'd be really interested if anyone can tell me what's happening when I interact with the phone and why the sounds almost perfectly match what I'm doing. From a sound design point of view, I think it sounds great and I'll definitely be using this as source material where and when I can!

Answer 1

That's your phone's brain, son! Your computers will do that as well if their audio circuitry isn't isolated from the rest of the box.

I battled this issue a lot when I was doing sound design for theaters and playing the show back on a cheap laptop. You haven to have the gain cranked pretty high to pick it up or just have a beast of an amp, but I also noticed that the effect was much more pronounced when my machine was plugged in. I can see from your screen that wasn't the case, but you might try it plugged into the adapter and see if you can get better signal.

If you'd like to make recordings of electronics the "RIGHT" way - go pick yourself up a coil mic from this guy, they're amazing. Hard drives sound wicked. Jez's Coil Mics

Answer 2

This is one of my favorite kinds of glitchy accidental sounds.

I've had computers where the onboard sound is located right next to a USB port. The devices plugged into the USB port make a variety of sounds, from really subtle to chaotic.

With one of them, if I plugged my optical mouse into it, I was able control the pitch of it by lifting the mouse up and down.

As I recall, the previous generation of Mac Pros had this issue with one of the USB ports and the onboard 3.5 output.

Either way, fun recording can be had from them.