AM radio accepts every bit of electrical inteference out there including lightning strikes miles away. FM grew because it did not. I think I would invest in an inexpensive FM radio and if you still have interference I would suspect those switches or something in the wiring.

Move the radio to other locations around the house and see what happens. Lots of the white noise in AM can be caused by poor reception. If you have a lot of wiring and electrical appliances on the walls around the radio, these too can interfere with reception. You can improve AM reception by adding an AM antenna to it, but you can only do that if the radio has an external AM antenna connection. If you buy a new AM/FM receiver, you will notice that it comes with an external AM antenna for connecting to the back of the receiver. That's the type of antenna I am talking about.

Check with Radio Shack and see if they sell um-powered AM antennas that you can connect to the radio, but make sure that the radio has such a connection at its back.

I went back and re-read your message, and realized that the problem is with both AM and FM.

1. Move the radio to other locations around the house
2. Try external (not outdoors) antennas
3. Make sure that the electric ground rod near the electrical meter (outside the house) has been properly installed, and that the clamps are tight around the rod, and the electric box. Also, find out from an electrician if the ground wire should also be clamped to the plumbing in the house. I have no idea if this is a code requirement, but my house was built with the breaker box grounded in a "Y' type of connection.

Finally search "AM radio antennas" on the Internet. Here is one (cut & paste):
http://www.abc.net.au/reception/radio/am_antenna.htm