尖叫声在大脑中会有特殊的位置

Screams Have Special Place in Brain 尖叫声在大脑中会有特殊的位置

From VOA Learning English, this is the Health & Lifestyle report.

Have you ever thought about screaming?

A blood-curdling scream is a natural reaction to sudden, extreme fright. When people hear a truly disturbing scream they usually respond … quickly. But why are screams so useful in warning us of danger?

New research helps to explain why screaming is disturbing and useful.

Screams, like those we hear in horror movies, have a special quality that separates them from other noises we make and hear. These screams are recognized by people all over the world. People of all cultures and languages hear the same thing in a scream: fear.

"Every kid in every culture screams. Every adult in the context of a true fear response screams. So it's genuinely a feature of the human mind and brain."

David Poeppel is a neuroscientist at New York University. He wondered why screams are recognized the same way by people all around the world. So, he and his colleagues set up an experiment.

They recorded screams from movies and from volunteers who took part in the research. The scientists, however, did not measure the screams for loudness or pitch. Instead, they measure how quickly the sounds in the scream changed in volume.

It was in this area -- the change in volume -- where screams stand apart from other sounds.

The researchers found that screams occupy a special part of the acoustic¹, or sound, spectrum² that other sounds do not. Professor Poeppel says screams have a reserved place, a niche³.

"When we analyzed⁴ all the screams using these more novel techniques, it turned out that screams occupy this unique niche in the acoustic spectrum that's actually not used by other sounds for any other communicative function. So they really have a reserved place."

How we measure sound

Sounds are described in terms of their frequency. Frequency is measured in hertz (Hz.) A person who has normal hearing can hear sounds that have frequencies between 20 and 20,000 Hz. The most important sounds we hear every day are in the 250 to 6,000 Hz range.

Normal speech changes in volume at a low rate – about 4 to 5 Hertz or cycles per second. Screams, however, change in volume very quickly and very widely -- from 30 Hz up to 150 Hz.

When the volume of a sound changes that quickly it has a quality called “roughness.” The more roughness a sound has, the more worrying it is.

David Poeppel and his team found that car alarms, sirens, and alarm clocks also have this quality, this "roughness.”

"Car alarms, sirens, annoying alarm clocks, and so on. Sound designers happened to come across exactly this design feature without actually even trying."

The scientists then studied how this "roughness" changed brain activity. They asked the volunteers to listen to different types of screams and alarms in an MRI scanner. The researchers found that the greater "roughness" of a sound, the more it activates⁵ the amygdala. The amygdala is an area deep in the brain that answers to fear.

"The amygdala acts like a gauge⁶ that says 'wow, this sound has a lot of roughness in it, that's particularly alarming and scary.'"

Screams, it turns out, are a direct link to the part of our brain that tells us if we should be afraid or not. People who hear these rough sounds are also more likely to react to them very quickly.

Professor Harold Gouzoules teaches psychology⁷ at Emory University in the United States. He studies screams in animals and humans. Mr. Gouzoules says screams played a very important evolutionary⁸ role in our survival.

"The properties of sounds that evolved to serve in communication are tailored to fit their needs. A scream isn't really so much to announce 'Hey, watch out, there's danger around here.' We have language. We can be far more precise in specifying⁹ our danger. A scream is to say 'I'm in trouble, I need help, and I'm over here.'"

Now, we know why a scream …

… gets so much attention, so quickly.

Mr. Poeppel and his team wrote their findings in the journal Current Biology.

And that’s the Health & Lifestyle report for VOA Learning English.

Words in This Story

bloodcurdling – adj. causing great horror or fear : this is a very common adjective used to describe screams

nightmare – -n. a dream that frightens a sleeping person : a very bad dream : a very bad or frightening experience or situation

pitch – -n. the property of a sound and especially a musical tone that is determined¹⁰ by the frequency of the waves producing it : highness or lowness of sound

vibration¹¹ – -n. a continuous slight shaking movement : a series of small, fast movements back and forth¹² or from side to side

frequency – [count] technical the number times that something (such as a sound wave or radio wave) is repeated in a period of time (such as a second)

Hertz – [count] technical a unit used for measuring the frequency of sound waves — abbreviation Hz

evolutionary – adj. of, relating to, or in accordance with a theory of evolution, especially in biology.

1 acoustic   

adj.听觉的，声音的；(乐器)原声的

参考例句：

• The hall has a fine acoustic.这个大厅的传音效果很好。
• Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。

2 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

3 niche   

n.壁龛；合适的职务(环境、位置等)

参考例句：

• Madeleine placed it carefully in the rocky niche. 玛德琳小心翼翼地把它放在岩石壁龛里。
• The really talented among women would always make their own niche.妇女中真正有才能的人总是各得其所。

4 analyzed   

v.分析( analyze的过去式和过去分词 )；分解；解释；对…进行心理分析

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
• The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程，因为对他来说，爱是个不可分析的迷。 来自《简明英汉词典》

5 activates   

使活动，起动，触发( activate的第三人称单数 )

参考例句：

• Activates the window and displays it in its current size and position. 激活窗口，保持当前的大小及位置不变。
• Pulling out the alarm switch activates alarm and pushing it deactivates it. 闹钟的开和关是通过拔出和按入闹铃开关实现的。

6 gauge   

v.精确计量；估计；n.标准度量；计量器

参考例句：

• Can you gauge what her reaction is likely to be?你能揣测她的反应可能是什么吗？
• It's difficult to gauge one's character.要判断一个人的品格是很困难的。

7 psychology   

n.心理，心理学，心理状态

参考例句：

• She has a background in child psychology.她受过儿童心理学的教育。
• He studied philosophy and psychology at Cambridge.他在剑桥大学学习哲学和心理学。

8 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

9 specifying   

v.指定( specify的现在分词 )；详述；提出…的条件；使具有特性

参考例句：

• When we describe what the action will affect, we are specifying the noun of the sentence. 当描述动作会影响到什么时，我们指定组成句子的名词。 来自About Face 3交互设计精髓
• Procurement section only lists opportunistic infection drugs without specifying which drugs. 采购部分只说明有治疗机会性感染的药物，但并没有说明是什么药物。 来自互联网

10 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。

11 vibration   

n.颤动，振动；摆动

参考例句：

• There is so much vibration on a ship that one cannot write.船上的震动大得使人无法书写。
• The vibration of the window woke me up.窗子的震动把我惊醒了。

12 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。