A B757-200 CAPTAIN REPORTS ON THE EXCESSIVE NOISE LEVELS IN THE COCKPIT AND CABIN REACHING 77.2 DECIBELS WITH THROTTLES UP AND ALL PACKS AND RECIRC FANS ON. COCKPIT AND ATC COMMUNICATIONS EXTREMELY DIFFICULT.

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AFTER TKOF WE FOUND THIS ACFT IS VERY LOUD WITH THE THROTTLES UP AND HIGH DUCT PRESSURE. WE TURNED OFF THE R RECIRCULATION FAN -- NOT MUCH HELP. ON APCH; WE ALSO HAD LEFT PACK OFF JUST SO FO AND I COULD HEAR EACH OTHER. I ENTERED THE FOLLOWING RPTING MESSAGE TEXT INTO ACFT MAINT SYS: 'COCKPIT AIRFLOW EXCESSIVELY LOUD INFLT EVEN WITH R RECIRCULATION FAN OFF VERBAL COM DIFFICULT.' PER FLEET TECHNICAL CAPT; I ALSO TAKE SOUND LEVEL READINGS WITH MY EXTECH 407732 SOUND LEVEL METER AND FORWARD THEM TO HIM AS WELL AS MAINT. THE INFLT READINGS WITH ALL PACKS/RECIRCULATION FANS ON WAS 77.2 DECIBELS; AND IT CAME DOWN TO 76.4 WITH THE R RECIRCULATION FAN OFF. TURNING THE L PACK OFF ALSO BROUGHT THE SOUND LEVEL DOWN TO 71.5 DECIBELS. FOR COMPARISON; A B767-300 WITH EVERYTHING ON NORMALLY IS 71-72 DECIBELS. THIS MORNING I DISCOVERED THAT MAINT SIGNED OFF MY WRITE-UP AS FOLLOWS: 'WITH BOTH PACKS AND RECIRCULATION FANS ON DECIBEL READING 75. WITH R RECIRCULATION FAN OFF DECIBEL READING 73. OK PER SVC TIP MAINT MANUAL.' I AM WRITING THIS RPT BECAUSE THIS SVC TIP EVIDENTLY DOES NOT REQUIRE ANY TESTING UNDER CONDITIONS THAT SIMULATE ACTUAL FLT -- WITH BOTH ENGS RUNNING AT INFLT THRUST LEVELS AND DUCT PRESSURES. COMPARING MY SOUND LEVEL READINGS WITH THOSE OF MAINT MAKES IT OBVIOUS THAT THE APU BASED TEST RESULTS IN FALSE LOW READINGS. BECAUSE OF THIS; ACFT X IS STILL SO LOUD THAT IT INTERFERES WITH COCKPIT VERBAL COM; MOST LIKELY NEEDS TO HAVE ITS DUCTWORK AND SIDEWALL SCREENS INSPECTED AND CLEANED; BUT HAS BEEN RETURNED TO SVC UNDER THE RESULTS OF AN INVALID GND TEST. SVC TIP MAINT MANUAL NEEDS TO BE REVISED IMMEDIATELY TO REQUIRE SIMULATION OF ACTUAL INFLT CONDITIONS -- WHICH MEANS READINGS DURING A PRESSURIZED HIGH PWR ENG RUN-UP WITH BOTH ENGS SUPPLYING AIR TO BOTH PACKS.