What was found
WHILE ON DESCENT AT APPROXIMATELY 5000', 250 KIAS, AND A CABIN DIF OF 2.4, AN AUDIBLE HUM/WHISTLING COULD BE HEARD FROM THE CABIN DOOR. IT SEEMS TO HAVE GOTTEN PROGRESSIVELY LOUDER WITH THE LAST FEW FLIGHTS. CORRECTIVE ACTION: ACCESSED AIRCRAFT AND REMOVED AND REPLACED DOOR SEAL. A WOW TEST KIT WILL BE REQUIRED TO PERFORM A LEAK CHECK OF THE SEAL. PLACED TOOLING ON ORDER VIA WEST STAR LOGISTICS AND WILL ADVISE MCC ON TRACKING. SM 4/13 REMOVED AND REPLACED MED SCAL REFERENCING AMM 52-10-35. LEAK CHECK GOOD.