The owner, licensee or operator of a visual or sound radio broadcasting station or network of stations, and the agents or employees of any such owner, licensee or operator, shall not be liable for any damages for any defamatory statement published or uttered in or as a part of a visual or sound radio broadcast, by one other than such owner, licensee or operator, or agent or employee thereof, unless it shall be alleged and proved by the complaining party that such owner, licensee, operator or such agent or employee has failed to exercise due care to prevent the publication or utterance of such statement in such broadcast.