Since January 2007 have been plagued by a constant humming noise sounding similar to a refrigerator. All appliances have been checked, rewiring done in property, mains checked for electricity (internal) and water (external) and all internal normal checks have failed to identify the source which is everywhere but nowhere in particular. Difficult for others to detect during the day. No mental health/physical health impairments! Social landlord who refuses to engage services of an engineer or other specialist. Help!

You stated that your home is a flat. Other tenants may be causing the noise with a humidifier or other such electrical motor. Have you had any conversations with your neighbors? Perhaps this humming is bothering them too.

If it's only bothering you, and the landlord is resistant to hiring an engineer, can you move? Perception of what a sound means varies with each person. Some sleep with a TV on. Others demand total silence. Deciding that a noise is bothersome is something we do, unconciously or not.

As a child, I was annoyed by a huge construction project taking place outside of my bedroom window, where there used to be forest. Telling myself that the sound of hammer and saw was comforting and safe worked. Now construction noises soothe me.