These are extremely low sounds that we humans are unable to hear, but fans, wind turbines and traffic can produce them.

次声波的频率非常低，我们人类无法听到，但是它能产生于风扇，风轮机和交通工具。

A flare-up on the western edge of southern California's largest wildfire sent more residents fleeing Sunday as high winds fanned the flames.

周日，在加州南部最大野火的西部边缘又发生了一场大火，导致更多的居民逃离，大风一直在助长火势。