I guess... and this is only my interpretation... but my take on "challenge" is just that -- having to do something you're used to falling back on or taking for granted and having to remove that very thing from the equation. Kinda like a game of Horse.
OK, this one is just with your left hand, your left eye closed, whistling Dixie, and you can hop on a foot of your choosing.
That sort of thing. You still have to make it in the basket, it's just that much more difficult, challenging, to accomplish.
And not to sound snarky (nyuck nyuck) but sound, IMO, is not half the experience of cinematography, which is what the challenge is about. Again, it's interpretation.
But hey, this isn't Palmer's Challenge, it's Wheatgrinder's, so I'm only chiming in as part of the community process.
Really, anything goes.