A really fun puzzle game! I've seen games that visually display sound as you walk or make noise, but none that let you guess your position by yourself based on the sound (kinda reminds of minesweeper a bit). Really simple and yet difficult puzzle. The 30 second timer was a bit extreme for me tho :D
I think instead of restarting the entire game after 30 seconds, it would be much more interesting if only the level restarts and the blocks you put disappear. That way you will not only have to guess, but to remember. Anyways good luck!