Alright, I've made it! =D Well, I got stuck again sadly, but at least I've been pretty far!
The echolocation is nice to use! I actually like the detuned piano sound it does. And the mazes are well designed: tricky, but not sadistic.^^ It's also great that the emitter is upgraded early (the first version being, as the game put it well, a bit lame :p).
The text is fun too! =) Sometimes a bit too mean toward the player. I liked when the character made fun of the player condition, and showed to be pretty insensitive. But him getting impatient or angry when the player has effectively trouble to move on might be a little too much. The game is actually challenging, and sometimes it can feel discouraging.
One thing especially that made the game hard is the absence of landmarks in the levels. Well, since it's a maze, I expect to get lost of course. But some distinct shapes or sounds in specific rooms could at least tell the player if they're going in circle. The emitter thing to shut down in the later levels helps greatly in that regards.
Cool concept anyway! It offers a good orientation puzzle, as well as an interesting claustrophobic and dark atmosphere (without being too scary).