Hi Mattbump,
Does the sound drop completely or only for a second or two?
Have you checked the audio settings on your Tivo?
Help & Settings > Settings > Audio > Dolby Digital - there are 2 options there Dolby Digital and Dolby Digital to PCM - ticking the PCM option usually solves sound dropouts.
Dave
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali