Howdy... I originally designed this kit so thought I would give a little background. Originally we were modding HD600s by adding lead weights...
I managed to find a link to the original report - I am not sure people can "hear" those frequencies necessarily but it would seem it may be...
I don't know if this is of interest but I did a bit of research into the perception of frequencies outside the the 20-20khz range in Uni I found a...
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