Sound is a mechanical wave that is an oscillation of pressure
transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing.
Sound also travels through plasma.
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声音是通过物体振动产生的声波。是通过介质(空气或固体、液体)传播并能被人或动物听觉器官所感知的波动现象。
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維基百科