So on the day I made these posts, I got home with a bunch of apps on my phone prepared to be able to prove that a significant difference in sound was occurring so that my wife would not insist that I am just crazy and making it up. only to find that the sound has completely gone!
At first I was ecstatic and I just lay on the bed finally able to relax in silence for the first time in months, but then I realised it wasn't the ending I was hoping for. Even though I am so glad that the sound has gone, I have no idea what was causing it. On that day my neighbour turned up for this first time in ages to move out the last bits of things from their house (they have moved to the other side of the road), I can only assume they had something in the garage nearest my place like a large wine cooler or some other thing that was running 24/7. Or, they have turned off whatever thing is causing the issue (the power is still on as I can see lights in various places). I need to try and catch them at a time that we are both around so I can try and find out what it was so that if someone else moves in the sound doesn't just start up again. Until then I have finally been able to get a decent sleep, and while my ever present insomnia remains, at least now when I lay in bed awake I dont have some rage-inducing drone going on all night (not including the wifes snoring).
If the sound does ever return, I will revisit this post....or you will find out about someone going postal in Takapuna claiming 'ThE NoIseS MAdE Me DO iT'