What was found
AIRCRAFT WAS GROUNDED: L1 DOOR DURING CLIMB OUT HAD A LOUD LEAK. FLIGHT ATTENDANTS REPORTED THE SOUND AS ABNORMAL. NO COCKPIT INDICATIONS WERE OBSERVED. AIRCRAFT LEVELED OFF BEFORE 10,000 FEET AND DECISION WAS MADE TO RETURN TO IAH. EMERGENCY WAS DELARED AND AIRCRAFT LANDED WIHTOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED UPPER AND LOWER FLAPPER SEALS ON FWD ENTRY DOOR IAW AMM 52-11-00. PREFORMED CABIN PRESSURE LEAK TEST IAW AMM 05-51-91. CABIN LEAK TEST SATISFACTORY.