Recently, a modder under the nickname Asterra returned to Fallout 3 and New Vegas and fixed a long-standing problem with the characters' lips.
During dialogues, the lip movements of NPCs very often get out of sync, skip pieces of syllables, and sometimes "speak" while the character is silent (or vice versa). He presented the Lip Motion Fix modification, which is designed to solve this problem.
The sound bug has been present in Fallout for a long time. For example, when a character tries to pronounce the sound "E" or similar sounds, the game glitches and "forces the speaker's lips to pronounce a neutral \"hm\"". This is especially noticeable on words like "Pip-Boy"; if you read the lips, you get "Pip-Bohm".
The Asterra modding project consists of two parts: "a comprehensive patch for dialogues in general and a patch that fixes the \"E\" error so that NPCs can pronounce this sound".
The Lip Motion Fix modification for Fallout New Vegas is available for free on Nexus Mods, the mod version for Fallout 3 received the same name.