amplitude probability density

例句：

1. 1. The sound of the music reached its maximum amplitude at the center of the room.
   音乐的声音在房间中心达到了最大振幅。
2. 2. The wave's amplitude is directly proportional to its speed.
   波的振幅与它的速度成正比。
3. 3. The amplitude of the signal can be measured using a spectrum analyzer.
   信号的振幅可以通过频谱分析仪测量出来。