who provides the speaking voice for Mardge Simpson's doctor?
I Married Marge:  In the episode, Marge worries that she may yet again be pregnant and drives to Dr. Hibbert's office. Dr. Hibbert:  His speaking voice is provided by Harry Shearer and his singing voice was by Thurl Ravenscroft, and he first appeared in the episode "Bart the Daredevil".
Harry Shearer