CDs, LPs, audiocassettes, DVDs, videocassettes, tapes, and CD-ROMs are not kept in the open stacks. Instead, you must look them up in the catalog, and then request them by call number at the rear circulation desk. Alternately, you can place a hold on them in the catalog (click or tap Hold This Item for Me), and in a day or two they'll be ready for you to pick it up at the circulation desk.
Note that many of the older recordings of MSM recordings say "Recording Arts Department Only." They are usually reel-to-reel tapes, and Recording Arts has the only copy. Until they are preserved and digitized, they are probably inaccessible. Contact the Orto Center for more information.