Sound

NetHack has no sound in the sense of audio-output from speakers, but your character in the game will hear many sounds, such as:

You hear water falling on coins.
You hear the footsteps of a guard on patrol.

Most sounds, like the above, have a definite meaning: the first tells you that there is a fountain on the level, the second that there is a vault. Other sounds can indicate one of many events, such as:

You hear a chugging sound.

This means a monster quaffed a potion, but you don't know which one.

You hear crashing rock.

There's a dwarf or some monster somewhere on the level that is creating tunnels through walls.

You can use this wiki to look up what a sound means by typing its message into the search box. You should be redirected to an article about the thing that caused the sound.