CLEVELAND (AP) — The Rock and Roll Hall of Fame is opening an exhibit about Graham Nash in which visitors can sing with a virtual Nash, and Nash will tell them if they’re good or not. The exhibit allows users to try to sing harmony with Nash, and they can email their results to themselves. The exhibit will also include the jeans and belt Nash wore to Woodstock, a painting Joni Mitchell made of Nash with their cat and Nash’s early handwritten lyrics to “Our House.” The exhibit opens October 17.