Narrative:

During the preflight inspection; we noticed in the logbook a couple of maintenance items concerning a noise emanating from the main cabin door during flight. The door and its seal had been inspected by maintenance and a leak check had been conducted; with 'ops checked good' (or words to that effect) in the corrective action. If memory serves; the most recent write up described the above noise as a 'hum.' we departed and climbed away from ZZZ uneventfully. While climbing through FL210 at a cabin psid of 7.5 we heard the noise from the cabin door. It was not a hum; rather a loud shout. The flight attendant later described it as sounding like a 'chain saw.' indeed; when the forward flight attendant went to call us; he had to go to the back of the aircraft and use the aft interphone as it was virtually impossible to communicate with that racket going on. We asked ATC for a level off and then a decent to try to make the noise less with a lower psid. A quick check of the cabin pressure and psid revealed no issues there; the cabin pressure was working normally. Indeed; checking the cabin alt vs aircraft alt in the QRH's manual pressurization schedule revealed that everything was fine. I tried calling maintenance in ZZZ as we should have still been within radio range; but I think that they may have gone home for the night. I also acarsed dispatch and then called maintenance control on arinc. It took a while to get through to them due to covid-19. When I appraised them of the situation; they told us to return to ZZZ. I talked to the flight attendants and talked the passengers to let them know what the situation was. It was a bit frustrating for the latter as the roar from the door was a soft hum aft of row X. To add insult to injury; a thunderstorm developed over ZZZ in our absence; so we had to hold...which was fine as dispatch still had to round up operations agents; gate supervisors; ramp agents; fullers etc. To add insult to injury; after we landed; the ramp was closed due to lightning. After we blocked; I gave maintenance a quick shout on the telephone and we offloaded the passengers and made our way over to the next aircraft for the flight to ZZZ1. Changing the subject; I would mention that the first officer (PF) did a fine job flying the aircraft and dealing with ATC whilst I was talking to the maintenance/dispatch/flight attendants/passengers and to the fas for taking care of the passengers.apparently there is something afoot with the door seal on aircraft xyz. I guess maintenance's efforts as to try to rectify any hums/roars/squeals etc hadn't solved the problem.

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Original NASA ASRS Text

Title: Air carrier Captain reported a loud hum during climbout emanating from the door and having to return to departure airport.

Narrative: During the preflight inspection; we noticed in the logbook a couple of maintenance items concerning a noise emanating from the main cabin door during flight. The door and its seal had been inspected by Maintenance and a leak check had been conducted; with 'ops checked good' (or words to that effect) in the corrective action. If memory serves; the most recent write up described the above noise as a 'hum.' We departed and climbed away from ZZZ uneventfully. While climbing through FL210 at a cabin PSID of 7.5 we heard the noise from the cabin door. It was not a hum; rather a loud shout. The Flight Attendant later described it as sounding like a 'chain saw.' Indeed; when the forward Flight Attendant went to call us; he had to go to the back of the aircraft and use the aft interphone as it was virtually impossible to communicate with that racket going on. We asked ATC for a level off and then a decent to try to make the noise less with a lower PSID. A quick check of the cabin pressure and PSID revealed no issues there; the cabin pressure was working normally. Indeed; checking the cabin alt vs aircraft alt in the QRH's manual pressurization schedule revealed that everything was fine. I tried calling Maintenance in ZZZ as we should have still been within radio range; but I think that they may have gone home for the night. I also ACARSed Dispatch and then called Maintenance Control on ARINC. It took a while to get through to them due to COVID-19. When I appraised them of the situation; they told us to return to ZZZ. I talked to the flight attendants and talked the passengers to let them know what the situation was. It was a bit frustrating for the latter as the roar from the door was a soft hum aft of row X. To add insult to injury; a thunderstorm developed over ZZZ in our absence; so we had to hold...which was fine as Dispatch still had to round up operations agents; gate supervisors; ramp agents; fullers etc. To add insult to injury; after we landed; the ramp was closed due to lightning. After we blocked; I gave Maintenance a quick shout on the telephone and we offloaded the passengers and made our way over to the next aircraft for the flight to ZZZ1. Changing the subject; I would mention that the FO (PF) did a fine job flying the aircraft and dealing with ATC whilst I was talking to the Maintenance/Dispatch/flight attendants/passengers and to the FAs for taking care of the passengers.Apparently there is something afoot with the door seal on aircraft XYZ. I guess Maintenance's efforts as to try to rectify any hums/roars/squeals etc hadn't solved the problem.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.