The most common cause of interference in your home comes from your own
appliances. Blenders, mixers, saws, blow dryers or any other small electric motor can
generate interference.
The offending appliances are easy to identify because of the noise they make while they are causing the interference. Other items aren't quite so easy to identify.
Any item that uses electricity in the home can generate noise. Items of particular concern are fluorescent lights, door bell transformers, fish tank pumps, water bed heaters, and heat pads.
Each of these can cause interference, electrical noise, without making any audible noise. Loose or overloaded electrical connections in your home can generate noise as well.