As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6545-STL - DURING DESCENT, LOUD POPPING SOUND STARTED COMING FROM THE MID CABIN AREA, FOLLOWED BY LIGHT SMOKE IN CABIN AND THE COCKPIT. MAINTENANCE PERFORMED AN INSPECTION AND FUNCTIONAL CHECK OF THE NR 1 PACK SYSTEM WITH NO DEFECTS NOTED. (S)