Elephants are able to know the difference between a man and a woman, and can tell an adult (成年人) from a child—all from the sound of a human voice. This is according to a study in which researchers played voice recordings to wild African elephants.

    The animals showed more fear when they heard the voices of adult Masai men. Usually Masai people hunt elephants, and this suggests that animals have grown to listen for and avoid them.

    Prof. Karen McComb and Dr Graeme Shannon from the University of Sussex led the study. They explained that in former research they had used similar experiments to show that elephants could tell—from the sound of a lion—whether the animal was a female (雌性) or a more dangerous male (雄性).

    Prof. McComb wanted to find out if the animals used their very sharp sense of hearing to recognize danger from humans.

    The scientists recorded Masai men, women and children saying, in their own language, “Look, look over there, a group of elephants are coming.” They also recorded Kamba men saying this phrase.

    Masai people often come across elephants, which can result in violent (暴力的) hunting. Kamba people, however, mainly feed on agriculture, which does not generally bring them into violent touch with the animals.

    When the team played recordings of these different voices through a hidden speaker, they found that elephant family groups showed more fear in response to the voice of a Masai man, than to a Kamba man's voice. And the adult male Masai voices caused far more violent response than the voices of women or boys.

    J.K. Rowling is the writer of Harry Potter, which is now one of the bestsellers in the world.

    J.K. Rowling was born in Bristol on July 31st, 1965. She has one sister who is two years younger than her. Both girls loved listening to their father reading bedtime stories to them. They especially loved stories about magical worlds. Rowling wrote her first story, called Rabbit, at the age of six.

    After she graduated from the university, Rowling worked as a translator in London. During this time, on a long train trip in the summer of 1990, the idea came to her of a boy who has magic but doesn't know it. In 1992 Rowling began to teach English. She lived with her baby daughter, Jessica, and spent much time finishing the first Harry Potter book for young readers. It appeared in June 1997. To her surprise, the book was greatly successful. The film came out in November 2001. Now Harry Potter series(系列) is popular with people of all ages and about 60 million books were sold in 200 countries.

    Why has the series been so successful? There are a few things. Many other magical stories take place in faraway lands or in past or future times. But Harry lives in modern England. He's also a very normal boy: polite, friendly, brave and clever. So when other children read about Harry, they can imagine being like him.

    J.K. Rowling is very happy with the success, and she is now busy finishing the whole series of seven books. She's writing full time and she's really enjoying life. She says she will go on living a normal life with her daughter and writing children's books.

    July is a month of fun-filled activities for kids and teens as long as you know where to find them. When you want some fun activities for July, consider these ideas happening in this month.

    "Don't answer it," I said to Sam. Our door in the inner city is constantly knocked on; our previous door in the suburbs rarely so. Sam has a full-time job and cannot spend his days answering requests to fix leaking baths or carry cash to the bank.

    Sam opened the door and it was Mervin.

    "There's a bird on the second floor," he said. "It's in trouble."

    Sam followed Mervin upstairs. Mervin pointed and turned to let Sam look. It was a pigeon, the most common of all birds, the bird most likely to foul (弄脏) your newly washed car. And it wasn't flying away. It was stamping in circles. As Sam bent to look, Mervin coughed, "Number two."

    Sam asked him to repeat that. "Number two," Mervin said. "The pigeon has been sitting in his own number two, and now it's stuck to his foot."

It had rained for five days, and the bird was young. It could have been sheltering in a     wet nest of its own waste, which had then dried on its foot, preventing it from flying away. The pigeon moved in a few more circles. Sam bent to take another look. Mervin said, "All right, then." and walked away.

    "Why does everyone think you must solve the problems around here?" I said to Sam when he returned with his story. "It's a bird. Just leave it on the stairs, and let nature take its course." Sam didn't agree. Then he went to the garage and emptied the cardboard box containing our imported camping mats. He returned with the gray pigeon in the box. He showed the bird to our children and they decided to keep it.

    They put its foot in the warm water bath and got rid of its waste. Immediately the pigeon erupted in a bomb of feathers and began flying.

    There's a world of difference between a horror movie and a comedy—the former scares you half to death while the latter leaves you rolling on the floor with laughter. But try watching them without the background music and you just might decide they're not so different after all. Music and movies have been closely connected since the beginning of the film industry—even before the voices of actors were recorded. In movies, music helps to provide a sense of time and place, convey ideas about the characters and, most importantly, draw emotions out of the audience.

    Studies have long shown that our heart rates and anxiety levels rise and fall depending on the speed of the music we hear. Using this knowledge, composers use sudden changes in film music speed to create fear among audiences. Slowing the speed of the music will have the opposite effect, bringing about a sense of peace or a dreamlike quality. The use of dissonant (不和谐的) tones and noises is another technique that heightens tension. Humans naturally become unnerved when we hear dissonant sounds because such noises are usually associated with danger, like those that animals make to warn against predators (捕食者).

    As crucial as it is, the best film music is subtle. All that audiences are supposed to feel is a heightened sense of emotion—they shouldn't realize what's causing it. Only when the music is taken out of the film should audiences understand its effects.

    In keeping with this principle, some filmmakers are even using what's called "infrasound" (次声波) to arouse fear. While we may not be able to hear it because its frequency is below the range of the human ear, infrasound has been proven to cause anxiety, tremble and even sorrow. For example, infrasound was used in the soundtrack of the 2007 horror movie Paranormal Activity, and audiences reposed extremely high fear levels despite the 1ack of action throughout the movie. "It doesn't affect everyone equally," said British science writer Philip Ball, author of The Music Instinct, but he predicted that "we will see more of it used in movies in the future".

    I always feel sorry for world leaders busy dealing with fights between nations. When my three children were young, most days it was hard to keep my house from becoming a battlefield.

    It got worse as they grew older. Three years ago, Zack, then 16, couldn't make it through a day without making his sisters, Alex 11 and Taryn 9, angry.

    My husband and I tried to be understanding the boy at such an age. We reasoned, punished, and left heartfelt notes on his bed about how he was hurting our family. His answer was "I say it because it's true."

    I even tried telling the girls to fight back. Bad idea. Now I had three children at war. Whatever I said to them, they paid no attention. When there was no way out, I told everything to my sister, Mary, in an email. She replied, "Don't email me. Email him."

    Our son was online every day, mailing and talking with his friends. Maybe he would actually hear me this way. I didn't say anything different, but email just took the tension away. There'd be no shouting or door banging. Zack wouldn't feel under attack.

    Zack didn't reply for days. When he finally did, his entire message was four small words. I smiled when I read them: "You're right. I'm sorry."

    The children still fought, of course, but Zack changed. Best of all, I now have a better way to talk with not one but three of them. I like it that they don't tune me out as much as they used to. They like not having to listen to me shouting to them. Or as Alex says, "You're so much nicer online."

    All I know is that the house is quiet. But we're talking.