科学家们听蓝鲸"唱歌"

Blue whales are still endangered, but their population is now on the rise again. And that might explain why the pitch of their songs has gotten lower. That’s according to John Hildebrand of the Scripps Institution of Oceanography in San Diego. He published a 2009 study on whale songs.
普斯海洋研究所的约翰．希尔德布兰说，蓝鲸仍濒临灭绝，但它们的数量有所回升。这也是它们歌声音调变低的原因。希尔德布兰在09年发布了一篇关于蓝鲸之歌的研究。

John Hildebrand: The animals had decreased the pitch of their songs by about 30% from the 1960s to today.

约翰．希尔德布兰：从上世纪60年代至今，这种动物已经将他们歌声的音高降低了大约30%。

For example listen to this blue whale song from the year 1964. Now listen to a song from 1997.

例如，请听1964年的蓝鲸之歌。现在再听1997年的歌声。

The pitch got lower, Hildebrand believes, because there are more whales now than several decades ago.

希尔德兰认为，音调变低是因为现在蓝鲸数量比几十年前多。

John Hildebrand: The hypothesis that we’re putting forward is that the shift downward in frequency is a response to the increasing population of the animals. As the densities go up, the distance to the closest females is shortened, so you don’t have to have a song of high amplitude.

约翰．希尔德布兰：我们所提出的假说是声音频率下降是对蓝鲸数量增加的响应。当蓝鲸分布密度上升，他们距离附近的母鲸的距离缩短，就无需高歌了。

In other words, whales don’t have to project their song as far in order reach a female, so they’ve literally changed their tune.

换言之，蓝鲸不需让他们的歌声传播很远就能到达母鲸的耳边，所以他们自然要调整曲调啦。