Sound waves

[Bing's effort at three hums]

Waking up this morning, I thought that I could hear two hums and I decided that one of them was the radiator and that the other was a car sitting in the road outside, engine idling. BH peered out of the window and asserted that there was no such car in the road.

Worked at it a bit harder, and I got up to three hums, sometimes four. The first two, plus one for noises from pipework elsewhere in the house, and another for noises in the ear, that is to say, noises arising from a different kind of pipework.

But eventually I decided that BH was right, and that I was hearing two hums from the two radiators in the room concerned. Radiators that differed in that one was much nearer and the other was the one that needed bleeding from time to time, despite looking identical and being at the identical height to the other. Enough difference to account for the slightly different hum.

What would my two brothers, both with musical ears, have made of it all?

PS: a little later: it now turns out that the nearer radiator is more or less permanently turned off. But there are pipes running under the floor boards there and hot water will be moving when the heating clicks in. All far too complicated for this time in the morning, that is to say just after 09:00.

References

Reference 1: Study explains how sound waves travel through disordered materials: This work may lead to new heat- and shatter-resistant glass for smartphones and tablets - Amit Malewar, Tech Explorist - 2021. The source of the snap above.