United B772 over Pacific on Aug 5th 2014, musical windshield

A United Boeing 777-200, registration N212UA performing flight UA-200 from Guam, GU (USA) with 231 passengers, was enroute at FL370 about 900nm east of Guam about 2 hours into the flight when the crew decided to return to Guam due to a whistling windshield that made communication in the cockpit difficult. The aircraft landed safely back in Guam about 5 hours after departure.

The airline reported that an issue with a seal in the windshield had occurred.

Passengers reported the captain announced there was a high pitched very loud sound in the cockpit distracting the pilots, work that had been done to fix a windshield seal hadn't succeeded.