What was found
ISSUE-CREW REPORTED UPON TAKEOFF, VERY LOUD STATIC/FEEDBACK COMING THROUGH HEADPHONES AND UNABLE TO HEAR ATC, FLIGHT DECK, FA, & PAX. ONLY WAY TO HEAR ATC WAS THROUGH SPEAKER. STILL WAS UNABLE TO ESTABLISH COMMS INSIDE THE CABIN (PILOT TO PILOT) FA NOTED WHEN PILOT PA WAS MADE TO PAX ANNOUNCEMENT, IT WAS UNINTELLIGIBLE. MX REPAIRED SUSPECT SOLDER CONNECTION ON FO'S SIDE HEADPHONE JACK TERMINAL AND REPAIRED BROKEN SOLDER CONNECTION ON CAPTAIN HAND MIC AUDIO JACK. MX ALSO RERACKED BOTH ICU'S ALL OPS TEST COMPLETED WITH NO DEFECTS NOTED.