Cave sounds never play

What I expected to happen was...:
Cave sounds ((cave) ambience) would dynamically play whilst exploring

What actually happened was...:
I never heard a single cave sound after playing on a singleplayer world (amplified+hardcore) for a good three hours, even whilst exploring dark caves.

Steps to Reproduce:
1. Try playing on a single player world for a while, perhaps with my specifications (amplified+hardcore) and attempt to trigger cave sounds