What was found
DURING CRUISE WITH A DIFFERENTIAL PRESSURE OVER 4.5, THERE IS A LOUDLY NOISE COMING OUT OF 2L WINDOW. MASKING CREW AND ATC COMMUNICATIONS IMPOSSIBLE, CREW DECIDED TO RETURN TO EDR.CORRECTIVE ACTION:WAS FOUND 2L WINDOW SEAL DAMAGED, CAUSING A PRESSURIZATION LEAK, REMOVED AND REPLACED 2L WINDOW SEAL IAW AMM 56-11-11 PAG 401, PERFORMED PRESSURIZATION LEAK TEST IAW AMM 05-51-24 PAG 201 TO 209, WITH SATISFACTORY RESULTS.