radio sweeper

The hoax was complete with telling radio sweepers done in-studio.

Dry radio sweepers are voice only-no music or sound effects-whereas wet sweepers generally contain sound FX (also known as "sonic", a global term for all sound effects and elements used in a sweeper.)

A radio sweeper is a short, pre-recorded sample used by radio stations as segues between songs that give listeners a brief station identifier or promo, generally 20 seconds or less: "You're listening to the soft sounds of [NAME] radio.