You need a much bigger step to hear it change:
(I have to admit I'd much prefer if the second parameter was plain old frequency myself.)
sound = LoadSound ("beep.ogg", 1) Print sound chan = PlaySound (sound) For x#=22050 To 8000 Step -500 Print x# Print 11025/x# SetChannelRate(chan,x#/11025.0) m=MilliSecs() While MilliSecs()<(m+100) Wend Next
(I have to admit I'd much prefer if the second parameter was plain old frequency myself.)