ORA_DICT_OBJ_OWNER returns an owner of the object acted upon by the event as a VARCHAR2 datatype.
SQL> SQL> DECLARE 2 owner VARCHAR2(30); 3 BEGIN 4 owner := ora_dict_obj_owner; 5 dbms_output.put_line('owner:'||owner); 6 END; 7 / owner: PL/SQL procedure successfully completed. SQL>