Seems it might be known as infrasound, that destructive low frequency sound technique I spoke of. I couldn’t elaborate however, as my eyes glazed over pretty much the minute I found a relevant webpage on the subject.
I don’t think you can hear infrasound and you can hear a drill so my unscientific brain deduces that we’re not facing the same problem here. Anyway I don’t think Bosch make drills that can do that so we’ll be OK. If anyone with glasses and a large head wants to put me straight I’ll be all ears, even if my eyes are a bit shut.