DisembAudio has a mechanical-sounding voice (unlike Tom Servo and Crow T. Robot) and was initially created to periodically recite a line from the movie being riffed to help the viewer keep the audio and the original film in synch. Occasionally, DisembAudio will interact with Michael J. Nelson and his co-riffers (if any) for comedic purposes.
The character was fully animated for the Rifftrax short Shake Hands with Danger, in which he is shown digitizing Mike (who arrives normally), Kevin Murphy (who is transformed into a box of popcorn) and Bill Corbett (who becomes a blow-up parrot). As the three digital performers remain onscreen throughout the short, this was a clear attempt to bring a fuller, more MST3K-like experience to RiffTrax. This short is available on The Best of Rifftrax Shorts, Volume One.
Behind the scenes
For many years, the voice actor for DisembAudio was not known. In a 2012 Reddit interview, Kevin Murphy refused to answer who the magical voice of DisembAudio was when inquired, saying he would go to his grave with that knowledge in hand.