Bobby Osborne grew up helping run the family general store in Thousand Sticks, Kentucky, and knew nothing about bluegrass until a late-night WSM broadcast of Earl Scruggs playing Cumberland Gap bounced off the ionosphere and into his valley. He dropped out of high school to form a band with his brother Sonny, then was drafted into the Marine Corps in 1951, wounded in Korea and awarded a Purple Heart before returning to music in 1953.

This episode explains the advice from Ernest Tubb that changed everything: drop the guitar and pick up the mandolin so its bright, percussive chop would frame rather than smother his high tenor. From there the Osborne Brothers flipped bluegrass harmony upside down by putting the lead melody on top of the vocal stack, recorded Rocky Top and Kentucky, which became official state songs, joined the Grand Ole Opry in 1964, and were named CMA Vocal Group of the Year in 1971. In 2017, at roughly 85, Bobby released the album Original with Vince Gill, Sam Bush, Del McCoury and Sierra Hull and earned a Grammy nomination.

• How skywave propagation let a Nashville radio signal reach isolated Appalachian valleys
• The acoustic physics of why a mandolin suits a tenor voice better than a dreadnought guitar
• Why a high lead vocal cut through AM static and engine noise in 1950s car radios
• Teaching bluegrass in Hyden, Kentucky and writing Windy City, later recorded by Alison Krauss
• Dying in 2023 at 91 as the oldest standing member of the Grand Ole Opry