Correct way to solve 9-?-5 ? ( Spoilers )

[Talzor]

I just finished 9-?-5 and was wondering if I found the intended solution.
The symbols fade out over the preliminary puzzles so first I tried to adjust my brightness/contrast (it is a ? after all :) ) but this made no difference. Then I used the sound clues to figure out that the valid cell are in an # pattern, but after that I could find no way to ascertain which of the valid cells contain circles so just resorted to brute forcing it by connecting all end points of the # with all others in both possible ways. This just felt wrong to me, all other puzzles have been so amazingly elegant (love the game btw, the puzzle design is so, so good). So my question is, have I missed something about 9-?-5 ?

[artless]

Hint:
You get the half correct sound when rule 1 is met, and rule 2 is not.

[Talzor]

ah, true. That does help narrow it down further, so there's less trial and error

[artless]

The intended is solution is:
Visit most of the boxes. If you got a half-correct feedback, There's no circle in not visited boxes.

[tstaffor]

Originally posted by artless:

The intended is solution is:
Visit most of the boxes. If you got a half-correct feedback, There's no circle in not visited boxes.

Is there any way to figure it out for deaf players? Also, why is this part of world 9? I thought 9 was focused on corners but this has nothing to do with that.

[gatesda]

A small shake or flash on the rule circles/bars would let deaf players solve it. Also useful for players like me who just happened to be playing without sound. (Hadn't bothered to put on headphones.)