Weird,

using headphones, I first clicked on the 8Khz button and then jumped to 12 and then to 22K when I heard nothing.

I went down to 21, I heard a faint something, and then when I got them all in a row I realised that I couldn't easily hear above 16, but I could faintly hear the 21 Khz one. Maybe I need an equaliser.

My father hears constantly what he describes as "a stream of water running" and his mother also was very hard of hearing in her last years. So I am probably also going to be accepted in the "Say that again, son?" hall of fame soon.