Answer the following question: Given the following passage  "In 1926, Universal opened a production unit in Germany, Deutsche Universal-Film AG, under the direction of Joe Pasternak. This unit produced three to four films per year until 1936, migrating to Hungary and then Austria in the face of Hitler's increasing domination of central Europe. With the advent of sound, these productions were made in the German language or, occasionally, Hungarian or Polish. In the U.S., Universal Pictures did not distribute any of this subsidiary's films, but at least some of them were exhibited through other, independent, foreign-language film distributors based in New York, without benefit of English subtitles. Nazi persecution and a change in ownership for the parent Universal Pictures organization resulted in the dissolution of this subsidiary.",  answer the following question. Note that the answer is present within the text.  Question: What allowed the language to be a factor?
Answer:
the advent of sound