Câu hỏi:

Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each of the numbered blanks.

Surround sound first showed up with Walt Disney's "Fantasia" in 1941. To show the movie with surround sound, a movie theater had to spend $85,000 for a special setup that included custom loudspeakers and required two projectors, one running the film and one track of audio plus a second one (16) _______ to four special audio tracks.

Because of the (17) _______ , the full surround-sound system was only installed in two theaters: one in Los Angeles and (18) _______ in New York. Many theaters offered surround sound as the magnetic-based sound became popular, allowing four or even six channels of sound. Dolby A noise reduction allowed films to have stereo optical tracks. (19) _______ , even Dolby A couldn't compensate for the level of noise if more than two optical tracks were put on the film. A major breakthrough in surround sound came (20) _______ Dolby Stereo was created.

that included custom loudspeakers and required two projectors, one running the film and one track of audio plus a second one (16) _______ to four special audio tracks.