听力文摘：人类听不见的声音（在线收听）

The Lowest Note in the Universe

宇宙中的最低音

It's coming from a black hole in the Perseus Cluster, about two hundred fifty million light years away.

宇宙中的最低音是由距地球约两亿五千万光年的

A black hole? And outer space? That makes sound?

英仙座星期群中的一个黑洞发出的。

What's happening out there is that intergalactic gas has concentrated around a cluster of galaxies, forming a cloud.

那里的星际气体已集中在星系群周围形成了云层。

A massive black hole is sending out jets of particles that crash into the cloud, causing pressure waves to ripple outward.

一个巨大的黑洞正在释放粒子喷流，这些粒子喷流又撞向云层，然后就产生了压力波向外界发出潺潺声的情况。

Some astronomers interpret these as sound waves.

有些天文学家把这种波解释成声波。

Of course, even if you call it sound, it's too low for anyone to hear.

当然，即使你称之为声音，但它也太低了以致没有人能听得到。

What note is it? They estimate the note to be a "B flat", about fifty-seven octaves lower than middle C.

他们估计这种声音属于降B调。比中央C低57个八度音阶。

Researchers now think that many black holes may produce such waves, which can affect the way galaxies, and even galaxy clusters, behave.

研究者们现在认为很多黑洞都会发出这种可以影响星系甚至是星系群的表现方式。