As the energy of wave motion is propagated outward from the center of disturbance, the individual air molecules that carry the sound move back and forth, parallel to the direction of wave motion. Thus, a sound wave is a series of alternate increases and decreases of air pressure. Each individual molecule passes the energy on to neighboring molecules, but after the sound wave has passed, each molecule remains in about the same location.
- energy [ˈenədʒi] n. 能量
- disturbance [disˈtə:bəns] n. 扰动
- back and forth [bæk - ænd - fɔ:θ] adv. 来回地
- alternate [ɔ:lˈtə:nit] adj. 交替的
- air pressure [ɛə - ˈpreʃə] n.气压
- neighboring [ˈneibəriŋ] adj.邻近的
