After years of hitting sour notes with artists, Pandora seems to have struck the right chord at last. The Internet’s biggest streaming-music service, Pandora unveiled its first hand-in-hand partnership with music creators and distributors on Wednesday through Merlin, a group representing more than 20,000 independent labels worldwide. Pandora will use its recommendation engine to match Merlin members’ musicians to the right listeners and will turn over metadata about that listening directly to artists for the first time, as well as set up customized channels for acts to communicate with fans. The partnership augurs a new age of harmony with artists for Pandora just two years after 125 top artists accused Pandora of trying to “gut” artist payouts and a year after Pink Floyd lambasted it with claims of trickery to cut royalties.