Beeping driving me insane!

[beepingmad]

Semi detached house next door is empty and has been for months. It was up for sale and the sign vanished months ago.

Since 8pm last night, there has been a constant beeping coming through the walls.
It's three beeps, then a gap the space of one more gap, then three more beeps. ON AND ON FOREVER!! I'm at home today, trying to work and I want to throw my laptop at the wall!

What is it? What can I do to stop it?
And since this is AIBU...please tell me you'd all be pretty pissed off too???

Smoke alarm battery alert? That would drive me insane! I keep a white noise app on my phone for when sounds distract me, something like that might help you?

Haha white noise irritates me too! I like silence!

Isn't the smoke alarm warning more intermittent than constant?

I reckon it's a smoke alarm battery too. Or something similar.

Can you contact the estate agent it was up for sale with?