Sorry, second answer regarding the bug: the feature isn't bugged, if you're talking about the typewriter effect?
If you still hear it while hovering menu items, it's normal, but turning it off gets indeed rid of the effect when the characters speak (so it works as intended).
Now, you use the word "animation" rather than "sound effect", so, if you're talking about the pace at which the text appears (since the text doesn't immediately appear), you can change the text speed (and putting it at the maximum gets rid of the typing animation).