Yeah, the audio games are rather niche compared to others but they still can make for a fun experience.
I wanted to go more about beeping. I think what you should look for is some way to remind the player about the mechanics easily, for example by having the proper tooltip on the screen. Typically in games like this, you introduce mechanic after mechanic slowly. In your game, this was done to some extent, but not really to walking and beeping. If you would separate these two as different levels, then it would work just fine.
For example, one level for walking until you go to the wall or something, then you will hear an explanation of what does this sound means.
And then level with beeping in which you have to go toward the spot. Then the game would explain what does this beeping means.