Hypersonic Effect (HFCs etc ...) 2009-01-01 23:18:50 Rather than once again take this post way off-topic, I thought I'd start another thread, as this interests me. For reference here's krabapple's post: http://www.hydrogenaudio.org/forums/index....st&p=606769It strikes me that there's something going on with HFCs (high-frequency components), what it is exactly and whether it's even related to what we might call "audio" (i.e. something we can hear) is another matter. What surprised me is that the study in question doesn't seem to have attempted to isolate the effect of HFCs. Wouldn't it have been more interesting if the source material was only HFCs - i.e participants in a room exposed to HFCs (> 25kHz) and then not exposed to HFCs who are then required to differentiate. That could easily follow ABX testing - i.e. this is the experience with HFCs, this is the experience without, now tell us when/whether A is X or Y. Mixing it all in with audible content seems to throw too many variables into the pot. I doubt whether the ears have a great deal to do with experiencing HFCs (which would explain the headphone result). My (complete) guess is that it's actually the skin that "feels" the ripples of very frequently changing air pressure. Perhaps we don't "consciously feel" this (in the sense that we identify that our skin feels the pressure fluctuations in the air) but it does something funny to our brains and we like whatever that is and then when that gets mixed in with the music we prefer the compound audible + inaudible effects to the purely audible. Ultrasonic disintegration, Sonochemistry and Ultrasonic cleaning all operate in the low ultrasound (20kHz+) range (http://en.wikipedia.org/wiki/Ultrasound). C.