This means that sound waves emanating from a supermassive black hole can travel many light years through this thin surrounding medium.

这意味着从超大质量黑洞发出的声波可以通过周围这种薄薄的介质传播数光年。

" Differences between air and water as a surrounding medium means that light interacts differently with a transparent organism's body tissues."

“空气和水作为周围介质，二者之间的差异意味着光与透明生物体的身体组织之间的相互作用不同。”