I’ve been bothered by a low frequency noise the last few days and I’ve yet to find the source. It’s not quite constant, can hear through my earplugs. It’s almo

I’ve been bothered by a low frequency noise the last few days and I’ve yet to find the source. It’s not quite constant, can hear through my earplugs. It’s almost like a busy set of hard spinning drives in a noisy old PC as heard from a floor below. I need to talk to my neighbour today to see if he’s got any new appliances/devices etc. And invite a friend over to see if they hear it too… Pretty sure I don’t hear it elsewhere so luckily not tinnitus but it’s been driving me a bit crazy!