What was found
EXTREMELY LOUD SQUEALING, GARBALLY, NOISE HEARD OVER BOTH HEADSETS AND BOTH VHF 1 & VHF 2 RADIOS. INTERPHONE COMM REMAINED NORMAL. INTERFERRENCE STARTED AT CRUISE FLT FL240 AND CONTINUED TIL APPROX 15,000 ON DESCENT. RETURNED TO FIELD. LANDING UNEVENTFUL. INSPECTED ANTENNAS FOUND NR 2 COM ANTENNA HAS HOLE IN L/E. REPLACED AND OPS TEST GOOD IAW AMM 23-11-26-000/400-801. CHECKED HISTORY OF NR 1 & NR 2 COM RT NO LIKE HISTORY FOUND. CHECKED RCAU HISTORY SN 414, FOUND DUPLICATE DISCREPANCY IN TEARDOWN REPORT. REPLACED AS A PRECAUTIONARY RCAU AND TESTED GOOD IAW AMM 23-51-01-000/400-801. REPORT ABOVE READ 2 COMM STATIC IS HEARD IN BOTH NR 1 AND NR 2 RADIOS. AC IS OK FOR CONTINUED SERVICE.