As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 2286: ON CLIMB-OUT, NOTICED A POPPING SOUND COMING FROM THE CAPTAINS SIDE WINDOW. AS CONTINUED TO PRESSURIZE IN THE CABIN, THE POPPING CONTINUED. ALSO, NOTICED THE SAME IN DESCENT. AIRCRAFT RETURNED TO FIELD. MAINTENANCE REPLACED CAPTAIN'S SIDE WINDOW IAW Q400 AMM 56-10-06-000-801 AND TR 56-017 AND 56-10-06-400-801. OPS AND LEAK CHECK GOOD. NO POPPING SOUND NOTED. AIRCRAFT RETURNED TO SERVICE.