Reverb in a mine tunnel

/!\ Be careful, extra loud sound /!\ Into an underground mine, I discovered a round tunnel. This one has an evocative reverb. When talking into the tunnel, it produces loud reverb on the walls and the ceiling. I'm talking and saying uninteresting sentences, it's only in aim to produce the curious sound. It's very near to be impossible to understand what I say, the sound is distorted, the low-pitched frequencies are reinforced.