Actually, his voice died. Henry Corden was the voice of Fred on the 1970s and 1980s Saturday morning series, and on the Cocoa Pebbles/Fruity Pebbles commercials up until recently. He was also Fred's singing voice on the original series. He was 85.
He was actually Fred's second voice. His original voice on the 1960s TV series was Alan Reed, a veteran voice actor who was also very prominent during the Golden Age of Radio. Reed also did Fred's voice on the Pebbles and Bamm-Bamm Saturday morning show in the 1970s, and also voiced a few other cartoon characters. But his most famous role was Fred. It was interesting because when Henry Corden took over after Reed died in 1977, Fred's voice ended up sounding very different, as if Fred had throat surgery or something. It sounded not at all the same as Alan Reed.
Anyway, this is another sure sign that I'm getting old.