I have one of those mosquito ringtones that only the youngsters are supposed to be able to hear. Mine is called 'atc_teenbuzz' and audacity tells me it plays at 15kHz. You can apparently find different versions up to 17.4kHz. On a couple of different computers, and on my old LG CU500, it played properly - really annoying, painful high-pitched noise. On my Moment, through the speakers or headphones, it plays at a lower pitch so that everyone can hear it and it's not painful at all (Or, the higher frequency is just being cut out altogether). This is whether it's played with the default media player or through the notification selection screen. I've never really used this much; my question is more a curiosity thing. I found this nifty page to test your hearing. I'm old (41) and I can hear 16kHz, and kinda feel some pressure from 17. Of course, into my teens I could tell when a TV was turned on in another room. I used to get so jealous of the kids in the next classroom when they got to watch (even educational) TV and my class had to actually listen to the teacher and learn something. I attached the tone if you want to check it out.