Sharraxaadda

There has been a high-pitched electronic/ mechanical squeeling sound all morning. It doesn't appear to be coming form one particular place, and varies in pitch and volume. It almost sounds like the whine of an electric saw or ringing in someone's ears, but no one seems to be using one nearby and it's definitely coming from somewhere in the neighborhood. It's pretty consistent - ringing steadily, changing pitch, then fading out briefly only to return a few seconds later. It's incredibly annoying. Anyone else hearing this? Any idea what's going on? Hopefully I'm not going crazy... lol