Well, what model Roamio, what is it connected to, via what kind of connection?
What are your sound settings on the output device?
What is your sound setting on the tivo (dolby/pcm)?
Is your default audio language set to english on the tivo?
Can you give examples of shows that arent working so that we can test them?
-Roamio Pro/Slide Pro
-Stream (Gotta go unplug the sucker one of these days!)