劍橋詞典a large increase in the force opposing a moving object as its speed reaches the speed at which sound travels 聲障，音障（指飛行物的速度達到音速時所產(chǎn)生的氣動阻力急劇增大） There is usually a sonic boom when an aircraft breaks the sound barrier . 飛機沖破聲障時，通常會產(chǎn)生音爆。 返回 the sound barrier