As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT CRUISE ALTITUDE FL 320 VERY LOUD WHISTLING SQUEALING, DESCENDED TO FL 210 & BECAME MORE DIFFICULT FOR CREW TO COMMUNICATE. SUSPECT AREA OF L2 OR L1 WINDOW. REPLACED WINDOW, PRESSURIZED ACFT. OPERATIONS CHECK NORMAL IAW AMM 56-11-0 2.