A little Cold War trivia for collectors of anti-Soviet kitsch: The United States once designed a compact record player to be airlifted over the Iron Curtain--where it would broadcast messages about human freedom to the communist populace. The device is one of the many recording artifacts on display this week in the Wilson Library at UNC-Chapel Hill. As host to the May 31-June 3 Association for Recorded Sound Collections conference, the library will exhibit everything from 19th-century wax cylinder players to $20,000 laser turntables. (Visitors can bring their own vinyl to test out on the pricey laser players.) Lectures on copyright, the future of digital audio and the early recordings of Russian romance and gypsy singing also promise to entertain and enlighten. Registration is $55 a day or $125 for all three days ($45 and $115 respectively for library members); for more information, call 962-1345.