Funny you should mention that (about TVs and higher frequencies) because,
living in a shared flat, I often pause outside the common room to listen
to see if the telly is on, and if it is at a low volume often I hear the
high-pitched hum of (what I assume to be) some sort of generator inside
the machine.
Perhaps I've got tinnitus, and should stop listening to Ventolin at loud
volumes!
Rob.