Are these speakers good enough??

[Ricardo]

FreqeunSee is an app on android that can measure it. It is also free but I purchased it to remove the ads.

Thanks for that. I just tested my logitech speakers and there are peaks at the 20KHz area which disappear when I switch the ultrasonic off. I haven't bothered testing the Creative speakers. I really wanted to play Ultrasonic at night to sleep easier. I could probably sleep on trickling stream but quiet is better for me