NEW YORK (AP) - For the past two months, Tenold R. Sunde has been toiling on 30 different studies of American humor. And soon, he and the CBS radio network will let listeners in on the gags. Sunde is the producer of a project called "A Sense of American Humor," which CBS Radio will air the weekend after this in 30 segments ranging in length from four to nine minutes. The series is hosted by Roger Mudd. It starts off by asking Steve Allen , Phyllis Diller, Jonathan Winters, Bill Cosby, Jean Shepherd, Carol Burnett and Stan Freberg what they feel makes Americans laugh and how it helps us.