I saw a post at a Facebook friend on Roscoe Holcomb. Above is part of an appearance on Pete Seeger’s “Rainbow Quest” television show. He performs “Little Birdy” and “Graveyard Blues.” Below, Holcomb plays “John Hardy” on guitar.
Wikipedia says that Holcomb was friends with John Cohen, who was in The New Lost City Ramblers. Cohen coined the term “high lonesome sound” to describe Holcomb’s singing. The description attached itself to bluegrass singing in general.
Cohen married Seeger’s half sister. The Wikipedia entry says that the Grateful Dead song “Uncle John’s Band” (with lyrics by Robert Hunter) is said to be based on Cohen.
Here is more on Holcomb.