As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF THE CREW REPORTED A CONSTANT CABIN TO COCKPIT CHIME AND WERE UNABLE TO COMMUNICATE WITH THE FLIGHT ATTENDANT. THE FLIGHT RETURNED TO LEX AND LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS THEN FERRIED TO CMH FOR FURTHER TROUBLESHOOTING. CMH MAINTENANCE TROUBLESHOT THE FAULT TO A DEFECTIVE PA AMP. THE PA AMP WAS REPLACED WITH NO FURTHER DEFECTS NOTED.