I'm glad you enjoyed it! I totally understand the difficulty curve thing. My goal was to create a pretty simple base mechanic, have a few tutorial levels to get people used to the concept, and then spend whatever time I had left stretching my wings and coming up with a more complicated level that would be more representative of what I would do if I decided to take the concept further. Since you can only go so far with bouncing a thing off a wall, I tried to see what I could accomplish by having objects in the environment interact with each other in a somewhat intuitive manner (if you notice, in the earlier tutorials, I tried to position the bottle or the cat in places you might hit with your sound waves, so you could see that the sound can interact with environment objects).
If I were to expand on this concept, that 4th level would definitely come a bit later on. I'd definitely need some kind of UI arrow pointing at the speaker for at least the first couple levels. And I know the stairs thing is a bit janky, I'd like to have a more intuitive solution for the future, as well as expand the house vertically and horizontally for different levels and have scores for optimal solutions and meters to limit how much you can shout (bar the fourth level, you can currently easily pass every level by just clicking rapidly in every direction).
Again, I'm really glad you enjoyed my game! This was my first venture into the puzzle genre, but I really enjoyed it!