Noise Canceling Headphones Problem

[BraedenP]

Hey,

I figured you physics geniuses might have an idea regarding what's happening to my headphones:

When under certain conditions (some of which I've nailed down, but others I can't figure out) the headphones will start making insanely loud "electric" noises that resemble the "zzzz" sound you'd hear coming from a Van de Graff generator.

Some conditions:

Firstly, this only happens when I am near my iPad (especially when the bulk of the headphone cord is near the iPad's back).

Secondly, it only happens when I have noise canceling enabled; if I turn it off while it's making the sparking noises, they stop.

Lastly, it happens ALL THE TIME when I am on the train and go past certain spots underground. It will also happen in random places around my University campus (usually when going past laboratories) and also in my basement at home.

I'm guessing it has something to do with magnetic interference from something (when the train starts moving and gets a jolt of electricity, they always act up) and when the train goes past power poles it usually does it, too.

Now I have a few questions:

1. Does anyone know why it would be doing this?
2. Is there a way to prevent this (short of buying new headphones)
3. If I can't fix it, is this damaging my hearing?

I'm very curious about this!

 

[rcgldr]

Electrical noise is getting into your headphone set, prior to the amplifier stage, which is then amplifying that noise. I've had video noise issues if I have a cell phone near a computer with an open case, and my wife's car can get noise over the car speakers from a cell phone doing some sort of cycle with the towers, but with the radio off, making me wonder if the amplifier stage is always on (or else antenna and harmonic effects are signicant in her car).