叮咚

叮咚	dīng dōng	(onom.) ding dong / jingling of bells / clanking sound
叮	dīng	to sting or bite (of mosquito, bee etc) / to say repeatedly / to urge insistently / to ask repeatedly / to stick to a point / (onom.) tinkling or jingling sound
咚	dōng	(onom.) boom (of a drum) / knock (on the door)