GEabbr.美国通用电气公司（=General Electric Coabbr.地面设备（=ground equipment）abbr.锗（=germanium）geoidn.大地水准面

1. Ambient noise may come from any direction.
   外界噪声可以来自任意方向。
2. Our second concern is with shot noise.
   第二个要讨论的是散粒噪声。