I haven't heard his performances as those characters except for an example of his Herry Monster, and it sounds a lot like Jerry's Herry, but with a slighy speech impediment, for whatever reason - not quite to the extent of Baby Bear's, but it's still noticable.
Welcome to the Muppet Central Forum!
Sesame Street Classics on YouTube
Sesame Street debuts on Netflix
Back to the Rock Season 2
Sam and Friends Book
Jim Henson Idea Man
Bear arrives on Disney+
.