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Ears are for hearing-everyone knows that. But for a creature called the Cuvier's beaked whale, hearing starts in the throat, a new study finds.

The observation might help explain how all whales hear, researchers say. The work might also help scientists understand how animals are affected by underwater sonar. This radar-like technology, used by some ships, sends out sound waves to detect and locate underwater objects.

The Cuvier's beaked whale belongs to a group called toothed whales. Toothed whales dive deep into the ocean in search of food. As the whales hunt, they produce sounds that bounce off objects and then return to the whales. This process, called echolocation, allows the animals to "see" the shape, size, and location of their prey, even when they're 1000 meters deep under the sea, where it is totally dark.

To better understand how the whale hears, researchers from San Diego State University in California took three-dimensional X rays of two dead Cuvier's beaked whales and used the images to create a computer model of a Cuvier whale's head. Then, they modeled the process of sound traveling through the head.

When the researchers used their computer model to track how sound waves travel in the whale's head, they were surprised to find that sounds coming from right in front of the whale actually travel under the animal's jaw. From there, sound waves move through the throat, into a hole in the back of the jaw, and finally to the pad of fat near the animal's ears.

用喉嚨聽聲音

每個人都知道，耳朵是用來聽的。但一項新的研究發現，對于一種叫做鵝嘴鯨的生物來說，聽的過程是從喉嚨里開始的。

研究人員說，進行觀察可能有助于解釋鯨魚是怎樣聽的。這項研究有可能幫助科學家弄懂水下聲吶對動物的影響。聲吶在技術上與雷達相似，有些船只使用聲吶，通過發射聲波的方法探測并確定水下物體的具體位置。

鵝嘴鯨屬于齒鯨一類。齒鯨尋找食物時要潛到海洋深處。當齒鯨獵食時，它們會發出聲音，其聲波會從物體上反彈回來，回到鯨魚那里。這個叫做回聲定位的過程，使鯨魚即使在水下1000米處完全黑暗的地方也能“看見”它們的捕食對象的形狀、大小和所在位置。

為了更好弄懂鯨魚是怎么聽的，位于加利福尼亞州的圣地亞哥州立大學的研究人員對兩頭已死的鵝嘴鯨拍攝了三維X射線照片，利用這些圖像制作了一個鵝嘴鯨頭部的計算機模型。然后，他們模擬了聲音通過鯨魚頭部的過程。

當研究人員利用計算機模型跟蹤聲波通過鯨魚頭部的過程時，他們驚奇地發現，在鯨魚正前方的聲音實際上是通過鯨魚的頜下傳進來的。聲波從頜下通過鯨魚的喉嚨，進入頜后面的一個孔，最后才傳到鯨魚耳朵旁邊的一塊脂肪上去。（注意斜體詞的譯法）

Exercise Protects Your Brains

Athletes and people who exercise not only have better bodies, they have better brains too, a host of studies have now firmly established.

A review of studies published earlier this month, in fact, found that a balanced diet and regular exercise can protect the brain and ward off mental (A) d.

Other (1) r has focused just on the effects of exercise. The bottom line: Exercisers learn faster, remember more, think clearer and bounce back more easily from brain injuries such as a stroke. They are also less prone to depression and age-related cognitive (B) d.

But why should a mindless half-hour on a treadmill (C) a your brain? Exercise, like hunger, is a stress on your body. "And sometimes," said Fernando Gomez-Pinilla of UCLA, "stress can be good." Because it burns calories so quickly, aerobic exercise is a threat to the body's energy reserves. Heeding this danger, the body acts to protect one of its most (D) p, and energy-demanding, organs: the brain.

Unlike cells in less critical organs, neurons are (2) e vulnerable to disruptions in energy supply. "If deprived of energy for more than one minute," said Gomez-Pinilla, "the neuron dies." For that reason, he continued, "all the (3) p of the body is designed to protect the brain."

By acting as a mild stressor, exercise is an alternative way to spur many of the protective benefits (4) a with calorie restriction and the release of brain-building growth factors, said Carl Cotman, director of the Institute for Brain Aging and Dementia at the University of California in Irvine.

And exercise not only protects the brain; it actually improves brain (5) f. This may be one more way, theorizes Cotman, that nature helped ensure the (6) sof those who were particularly good at certain prehistoric activities, which in those days meant hunting and defending grub.

(A, B, C, D FOR CROSS, 1, 2, 3, 4, 5, 6 FOR DOWN. The first letters of the absents were given)

Hungry Scientists (1)

Four scientists get together for dinner. Their first names are Max, Charles, Fred, and Susan. Four place cards on the table show only their last names: Osmium, Tissue, Infinity, and Radian. Can you match the first and last names of each of the scientists from the clues below?

(1) Radians first name contains an "r". (2) No one's first initial appears in his or her last name. (3) Charles's last name is also an element.

上期Crossword答案

1. customer2. underage

3. adult 4. purchase

5. ministry A. developed

B. structure C. remaining

D. drivingE. survey

上期Illation答案