About AM6`s ultrasonics

[Voytek]

Thank you very much for yer kindness and more than sufficient explanations, CatMan. But tell me, do you have any technique to avoid headphones falling during a sleep? Do you use sticky tape or sth?

My speakers have 40-20,000hz range; is this sufficient for ultrasonics? Ok, ok; I`ll test them with testing mp3 from our beloved site!