Mel did do Elmer for awhile, but the actor who did it the most was Arthur Q Bryan. Bryan died in 1950. Many different actors did Elmer until WB broke up its animation dept in 1964. Here’s an old video of Bryan working for NBC. https://www.youtube.com/watch?v=OMPtM-VsBJk
Ted was on the staff of WFAA radio in Dallas when JFK was killed. His voice is heard on the recordings from that day. You can hear it on YouTube.