I am experiencing a lack of sound from both mobs and my avatar as well. I have tested this with multiple mobs, multiple times, and I either get the same or similar results.

While mobs do make their usual idle sounds most seem to lack their hurt sounds, death sounds, or both. 

Example:

Creeper: makes hurt sounds when taking damage, but no death sound upon dying

Zombie: no hurt sounds when taking damage and no death sound upon dying

This applies to my avatar as well, though it depends on how I took damage.

Example:

-Falling: I get the fall hurt sound upon hitting the ground

-Walking into sweet berry bush: no sound

Even though these are not game-breaking bugs, they still do affect my gameplay experience when playing in survival and, they are overall, quite a bit annoying.

Thank you for taking the time in reading this and I hope you are able to look into it.