『新东方在线托福听力』为托福考生准备了ETS托福TPO/【学术讲座】#38听力练习：What is the speaker mainly discussing?原文题目答案解析，TPO/【学术讲座】#38听力原文范文音频翻译。

托福TPO/【学术讲座】#38听力原文What is the speaker mainly discussing?【新东方在线】

请听今天科学课上的一段讲话。

Listen to a talk in a science class today.

我想告诉你们一个科学家们在20世纪90年代初在太平洋注意到的异常现象。

I want to tell you about an unusual phenomenon that scientists noticed in the Pacific Ocean in the early 1990's.

科学家们使用放置在北大西洋底的水听器来录制声音。

The scientists were recording sounds using hydrophones positioned on the ocean floor in the North Pacific.

水听器是一种特殊设计的水下麦克风，能让科学家收集水下声学数据。

Hydrophones are specially designed microphones that allow scientists to collect acoustic data underwater.

虽然水听器接收到的大部分水下噪音来自鲸鱼、船用发动机或地震，但监测这些水听器的科学家们发现了一些他们无法识别的声音。

While most of the undersea noises picked up by the hydrophones emanated from whales, ships' engines, or earthquakes, the scientists monitoring the hydrophones detected a number of sounds that they could not identify.

其中一种是规律的、音调持续上升的次声波系列，其波长很短，低于人类的听觉范围。

One was a regular series of rising infrasonic tones that have very short wavelengths below those humans can hear.

科学家将这些非常低频的噪音标记为“上扫音”。

The scientists labeled these very low frequency noises "upsweep."

起初，这些声音被认为是太平洋中鲸鱼迁徙时的歌声。

At first, these sounds were thought to be the songs of whales migrating in the Pacific.

然而，研究鲸鱼声学的科学家最终排除了这种可能性，而上扫音的来源仍然未知。

However, scientists who study whale acoustics eventually ruled out this possibility, and the origin of the upsweep sounds remained unknown.

那么，水听器探测到的这些上升音调究竟来自哪里呢？

So what is the source of the rising tones detected by the hydrophones?

这些声音最终被追踪到一个推断有火山地震活动的区域——南太平洋的一处海底山脉链。

The sounds were ultimately tracked to an area of inferred volcanic seismic activity — a chain of undersea mountains in the South Pacific.

一些科学家认为，如果这些山脉中有一座活火山，那么神秘的上扫音来源可能就是炽热的火山熔岩与冰冷的海水接触时产生的声音。

Some scientists believe that if these mountains contain an active volcano, the source for the mysterious upsweep sounds may be hot volcanic lava coming in contact with cold sea water.

At first, what did scientists believe was the source of the mysterious tones they recorded?

Why does the speaker mention "inferred volcanic seismic activity"?

Listen to a talk in a science class today.<br />I want to tell you about an unusual phenomenon that scientists noticed in the Pacific Ocean in the early 1990's. The scientists were recording sounds using hydrophones positioned on the ocean floor in the North Pacific. Hydrophones are specially designed microphones that allow scientists to collect acoustic data underwater. While most of the undersea noises picked up by the hydrophones emanated from whales, ships engines, or earthquakes, the scientists monitoring the hydrophones detected a number of sounds that they could not identify. One was a regular series of rising infrasonic tones that is a very short wavelengths below those humans can hear. The scientists labeled these very low frequency noises up sweep. At first, these sounds were thought to be the songs of whales migrating in the Pacific. However, scientists who study whale acoustics eventually ruled out this possibility and the origin of the up sweep sounds remained unknown. So what is the source of the rising tones detected by the hydrophones? The sounds were ultimately tracked to an area of inferred volcanic seismic activity, a chain of undersea mountains in the South Pacific. Some scientists believe that if these mountains contain an active volcano, the source for the mysterious up sweep sounds may be hot volcanic lava coming in contact with cold sea water.

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