Short story of a dome (or at least a barrier) that appeared over a city overnight - it may have been New York or Manhattan. There was not any explanation or claim of responsibility. An engineer could hear a B-flat tone that it produced and that was a clue to solving it. The dome/barrier was actually a test, as the perpatrators were evaluating it as for a more large scale use/attack. I read this between 1975 and 1990 in an anthology.
Not a movie or video.