That must be the naked body then. Clothing would (does) readily absorb high frequencies even in the middle of the audio band.
I was thinking about the comment that in the rain forest 'there are frequencies up to 100kHz'. In fact, a rain forest, especially when raining, would (probably) sound rather like hiss, the inter-station static on a VHF radio or a crackly record's run-out groove. In other words, a completely random wide-band noise. Is that relevant to speech or music in ordinary life? No. Would evolution have deliberately extended our hearing to catch all of these super-super high frequencies? No. The problem from a survival perspective is that if the hearing range is too extended, then we are unable to hear the predators because our hearing would be drowned-out with useless random noise from the wind rustling leaves and other HF details.
As I said, evolution is very frugal; we are neither provided with super senses nor inadequate ones. The senses we have are exactly right for the environment in which we live. No more, no less.
Alan A. Shaw
Harbeth Audio UK