There's a similar condition to this people have and that's "Humming" getting worse. It drives some people crazy!!. People with start off thinking someone has stopped outside their house with car engine running, then they think it's a power station or some factory noise pullution, they switch off all the power in their house, buy magnetic feild detectors and that they use to 'clean' their house from top to bottom of demonic magnetic feilds. They complain to the council's noise control department, who 'don't take any notice', then I heard of one guy who moved out of london into the country to get away from it, and the 'humming' followed him there, I don't know what happened to him. People take this thing really seriously, there is hum clubs around the world who have annual 'hum conventions', I am not making this up!!!
Anyway, there's a growing body of belief now (well in 2006 that was) that the humming sound is actually "caused by the person hearing it", the cause and effect of the humming are entwined somehow, the best theory is recent research (as far as I know) discovered that ear system has a muscle that operates automatically, and that something to do with a vibration in the control system, some kind of feedback loop like a microphone and speaker. Well anyway how I know all this is my ex-gf had it, I cured her before it took hold, with FM radio, then a pink noise CD, with a volume turned down as the weeks went on, her side of the bed. Biggest problem I think is the psychologic one, it's convincing the person who thinks they have it, that it's not something outside their body that's doing it, it's that they are hearing themselves hearing it.