What was found
ON CLIMBOUT PASSING FL 370 SUDDEN, LOUD, CONTINUOUS HIGH PITCHED NOISE EMANATING FROM SOMEWHERE IN THE FWD PEDESTAL/CENTER INSTRUMENT PANEL AREA. LEVELED AT FL 380, DECLARED EMERGENCY AND BEGAN DESCENT WITH NOISE CONSTANT. PASSING FL330, NOISE BEGAN TO GRADUALLY DECREASE AND WAS SILENT BY 32,700'. ABSOLUTELY NO ASSOCIATED INDICATIONS WHATSOEVER: NO ENGINE GAUGE INDICATIONS, NO PRESSURE ANOMALIES, NO AVIONICS MALFUNCTIONS, NOTHING - JUST A NOISE. R & R THE CO-PILOT'S WINDSHIELD IAW MM 56-10-00. LEAK CHECKED GOOD. COMPLETED OPS TEST OF RT WINDSHIELD ANTI-ICE IAW MM 30-40-00-201, OPS CHECKED GOOD.