Unfortunately only he can appreciate his own experience.
He gives a pretty decent explanation of what he is seeing in the Catalyst transcript. It's fascinating, as from his description it's a low resolution (due to the longer wavelength) of what you or I would see. Presumably he also sees things such as colours, but based on audio reflectivity rather than optical reflectivity?
Your point about only him appreciating his own experience is interesting, as the same question can be asked of all of us [1]. In audio, maybe apples and oranges are the same colour and strawberries are different? It would be an interesting application of a sonic camera, to render the image so that equivalent audio colours are consistently mapped to the same light colours.
[1] https://www.quora.com/Visual-Perception-Is-everyones-experie...
I have. His name is Daniel Kish [1, 2].
Apparently his visual cortex has learned to process sound rather then light, so he literally sees, based on the sounds he is hearing.
[1] http://www.abc.net.au/catalyst/stories/4441831.htm
[2] https://en.wikipedia.org/wiki/Daniel_Kish