Anyone else hear a low hum at night?

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Larkhill_Geoff · #1 Post by **Larkhill_Geoff** » Fri Jun 13, 2014 12:00 am

Odd one and probably nothing. For a few weeks now, out at night doing the bat surveys, I have been aware of a low hum: very low, more felt than heard, a sort of pressure in the ears. Worst in the small hours, worst when it is still, and it seems to come from no direction, or from the ground itself. I have ruled out my own kit and my own ears as best I can. I know the famous Bristol Hum and the Taos Hum and all that, and I know it is usually traffic, or a pump, or tinnitus, or a generator carrying on a still night. I am a sceptic by trade. But I cannot place this one and it is keeping me up, and the bats, oddly, go quiet in it. Anyone else out at night getting this?

Devizes_Mech · #2 Post by **Devizes_Mech** » Fri Jun 13, 2014 10:00 am

its a pump or a compressor somewhere geoff, they carry for MILES on a still cold night, you wouldnt believe how far. dairy out your way? sewage works? someone running a biomass boiler overnight? low frequency travels and travels and you cant tell where its from, thats the whole problem with it, your ears cant place a long wavelength. nine times out of ten its farm or industrial plant ticking over when the air goes still and flat. not saying it isnt annoying.

DowserDoreen · #3 Post by **DowserDoreen** » Fri Jun 13, 2014 6:00 pm

I will only say that the still cold nights are when the ground is most awake, in my experience, and that you are right it comes from below and not from a direction. I do not call it a pump. But I would not argue with Geoff, who knows more than I do, only note that the animals going quiet is the part the pump does not explain. A compressor does not hush the bats. Something does, out there, on the still nights, and the bats know it before we feel it.

Larkhill_Geoff · #4 Post by **Larkhill_Geoff** » Sat Jun 14, 2014 11:30 pm

Doreen, the bats are exactly what nag me, and I say that as the resident sceptic. Animals do not respond to a sewage works. I will keep logging it, time and temperature and where, and see if it has a pattern. Probably I will find the boiler and feel a fool, which would honestly be a relief. I would rather feel a fool than keep lying awake feeling the ground hum. I will report back if it does anything interesting.