Hey all. I have an update to this topic, we now know who the voice actors are for ToM.
I was having a conversation with Dr. Dave Zabriskie, the person who was in charge of sound at WMS during the production of ToM. I asked him about the ToM voice actors and he knew exactly who they were.
The male voice was performed by Mike Wadswoth, a good friend of Dave's. He's an opera singer with an "incredible low resonant bass voice and an infectious laugh."
The female voice was performed by Cathy Schenkelberg, who was dating a friend of his at the time. Cathy is an accomplished film/stage actor and comedian. Her daughter, Fiona Grey, who has a growing career as a singer/songwriter.
In any case, the mystery is solved! ToM was not Tina Fey, and now we can give credit where credit is due.