As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 731, LGW-PHL: DURING FLIGHT, THE CAPTAIN REPORTED DIFFICULTY HEARING RADIO TRANSMISSIONS DUE TO EXCESSIVE AIR NOISE IN THE COCKPIT. DIVERTED TO SNN. MAINTENANCE PLACED THE LEFT PACK ON MEL. SUBSEQUENT TROUBLESHOOTING DETERMINED THAT THE F/O'S WINDSHIELD AIR DIFFUSER WAS CRACKED AND A LOUD HUM WOULD DEVELOPE WITH THE PACK ON. REPAIRED DIFFUSER. NO FURTHER FAULTS.