What was found
AIRCRAFT WAS GROUNDED: LOUD NOISE FROM FWD SERVICE DOOR. ENTIRE FLIGHT. AT 13000 FEET FA CALLED COMPLAINING LOUD NOISE FROM FWD SERVICE DOOR. LOUD ENOUGH THAT WE COULD HEAR IT IN FLIGHT DECK WITH NOISE CANCELLATION. DECESION MADE TO RETURN TO GYE, FLIGHT DECLARED AND EMERGENCY AND LANDED OVERWEIGHT WITHOUT INCIDENT. MAINTENANCE PERFORMED CABIN PRESSURE LEAK TEST IAW AMM 05-51-91-79 0-801 AND DOOR SEAL - INSPECTION/CHECK IAW AMM 52-09-00-700-801. NO LEAK,NO SOUND AND NO DAMAGE FOUND ON THE SEAL, NO HISTORY.