From Longman Dictionary of Contemporary Englishsound barrierˈsound ˌbarrier noun → the sound barrier
Examples from the Corpus
sound barrier• In 1979, Stanley Barrett broke the sound barrier on land.• Fast fighter jets -- many traveling within earshot of the sound barrier -- will headline the shows.• I've even taken an F-15 jet to within a whisker of the sound barrier.• At the time of his death Campbell was unsuccessfully seeking backers for a jet-driven car to go through the sound barrier. 