I wonder whether people heard the hum more or less, quieter or louder during the lockdown when everything was so much quieter. Anyone know of any change?

I've heard the hum many times in different parts of the UK and its usually loudest on bank holidays - that is, the days when things are most quiet. I think I'm hearing my own blood pumping away - a kind of merged drum beat.

Now - I have also heard the associated "Hummadruz" too - which is more of an insect / bee drone. I recorded it on my camera but the audio couldn't pick it up. However I was walking though a field where there were many foxgloves, dry stone walls and bees around in high summer. Non hive bees will often live and buzz in their holes, so the hummadruz could be literally insects.

The low bassy drone in both the hum and the hummadruz makes it hard to pin point the direction - it's why you only need one bass speaker in most hi fi systems.