15 Are You Listening The Sense of Hearing

CHAPTER 1 What Is Hearing? SOUNDS MAKE WAVES IN THE AIR. THE WAVES TRAVEL TO YOUR EAR, AND YOU HEAR THE SOUND. Some sounds are high. These come in short, quick waves. Low sounds come in long, slower waves. Some sounds are so high or so low that people can't hear them. But, some animals can! Dogs, for example, can hear very high sounds. When we want to say how high or low a sound is we use hertz (Hz) and kilohertz (kHz). Younger people can hear higher sounds than older people. This machine is called a Mosquito. It makes a very high sound. Teenagers can hear it, but people over 25 can't. Teenagers don't like the sound of the Mosquito. If you want teenagers to stay away from a store, or another place, you can put one there. A good idea? Well, maybe, but teenagers came back with something new. They use the Mosquito's sound as a ringtone for their cell phones. Most teachers can't hear this, so teenagers can use their phones in class, and the teacher doesn't know!

第一章什么是听力？ 声音在空气中引起波浪。 声波传到你的耳朵里，你就听到了声音。 有些声音很高。这些都是短而快的波浪。 低沉的声音以长而慢的波传播。 有些声音太高或太低，以至于人们听不到。 但是，有些动物可以！例如，狗可以听到非常高的声音。 当我们想要表示声音的高低时，我们使用赫兹（Hz）和千赫（kHz）。 年轻人比老年人能听到更高的声音。 这台机器叫做蚊子。 它发出很高的声音。 青少年能听到，但25岁以上的人听不到。 青少年不喜欢蚊子的声音。 如果你想让青少年远离商店或其他地方，你可以在那里放一个。 好主意？也许吧，但青少年们带着新东西回来了。 他们用蚊子的声音作为手机的铃声。 大多数老师听不到这个，所以青少年可以在课堂上使用手机，而老师不知道！

CHAPTER 2 How Loud Is Loud? WATER, ANIMALS, DRUMS, AND MANY OTHER THINGS MAKE LOUD NOISES. High waves in the sea are louder than low waves. Why? Because the waves in the water make sound waves in the air, and high waves make higher, louder sound waves. The sea is often a noisy place, but some animals in the sea are very loud, too. The blue whale can whistle louder than the noise of a plane. Other whales can hear it thousands of kilometers away. Blue whales are the largest and loudest animals in the world. Some other animals are loud, too. You can hear a lion eight kilometers away, so you have time to start running. Howler monkeys live in groups. They shout really loud so that other groups stay away. We use hertz to say how high or low a sound is, but we use decibels (dB) to say how loud a sound is. A decibel meter is red above 80 dB because sounds louder than this can damage a person's ears. Loud music can be up to 150 dB. What was the loudest noise of all time? In 1883, on the island of Krakatoa, in Indonesia, a volcano exploded. Most of the island flew up into the sky. People heard the sound in Perth, Australia— 3,110 kilometers from Krakatoa! People near the volcano went deaf. It was probably 180 dB. The loudest possible sound is 194 dB.

第二章到底有多大声？ 水、动物、鼓和许多其他东西都会发出很大的声音。 海中的大浪比低浪更响。 为什么?因为水中的波浪会在空气中产生声波，而高波会产生更高、更响的声波。 海洋经常是一个嘈杂的地方，但是海里的一些动物也很吵。 蓝鲸的口哨声比飞机的噪音还大。 其他鲸鱼可以在几千公里外听到它。 蓝鲸是世界上最大、声音最大的动物。 其他一些动物也很吵。 你能听到八公里外狮子的叫声，所以你有时间开始奔跑。 吼猴群居。 他们大声喊叫，让其他群体远离他们。 我们用赫兹来表示声音的高低，但我们用分贝（dB）来表示声音的大小。 分贝计在80分贝以上是红色的，因为超过80分贝的声音会损害人的耳朵。 大声的音乐可以达到150分贝。 有史以来最大的噪音是什么？ 1883年，在印度尼西亚的喀拉喀托岛上，一座火山爆发了。 大部分岛屿都飞上了天空。 人们在距离喀拉喀托火山3110公里的澳大利亚珀斯听到了这个声音！火山附近的人都聋了。 大概是180分贝。最大的声音是194分贝。

Think about a band of musicians going down the street. When they walk away from you, what instrument do you hear last? The big drum. Its low sound travels in long waves. Long, low sound waves are very strong and go farther than short, high waves. A ship's foghorn sends out very low sounds to tell other ships where it is in a fog. This low sound is very loud, about 120 dB, and can travel 6 kilometers. Robert Foulis made the first foghorn in 1853. He heard his daughter playing the piano when he walked home one night, but at first he only heard the low notes. He understood that low notes travel farther. Loud noises wake us up... usually. Some people live near airports, but the planes don't wake them up. But if you don't live near an airport and a plane flies near your house, you wake up. Why? Because this isn't a normal sound where you live. The job of alarm clocks is to wake us up. Some alarm clocks are very loud. They can go up to 113 dB. The problem is that they can also wake up other people nearby. You can hear someone else's alarm clock as far away as 100 meters!

想象一下一群音乐家走在街上。 当他们离开你时，你最后听到的是什么乐器？ 大鼓。它低沉的声音以长波传播。 长而低的声波非常强，比短而高的声波传播得更远。 船上的雾角发出非常低的声音，告诉其他船只它在雾中的位置。 这种低沉的声音非常响亮，大约120分贝，可以传播6公里。 罗伯特·福里斯于1853年制造了第一个雾号。 一天晚上回家的路上，他听到女儿在弹钢琴，但起初他只听到低音。 他明白低音传播得更远。 巨大的噪音把我们吵醒。通常。 有些人住在机场附近，但飞机不会把他们吵醒。 但如果你不住在机场附近，一架飞机飞到你家附近，你就醒了。 为什么?因为在你住的地方，这不是正常的声音。 闹钟的作用是叫醒我们。 有些闹钟声音很大。 它们可以达到113分贝。问题是，它们也会吵醒附近的其他人。 你可以在100米远的地方听到别人的闹钟！

CHAPTER 3 How Soft Is Soft? WHERE IS THE QUIETEST PLACE IN THE WORLD? IS IT SOMEWHERE WITH NO PEOPLE AND NO CARS? THE ARCTIC? A LONG WAY UNDER WATER? There is a special room at Orfield Laboratories in Minnesota, USA. Sounds go in special spaces on the walls and the floor, so there are no echoes. The walls are very strong, so no sounds come in from outside. It's the quietest place in the world. You feel different in this special room. First, you may have to sit down. When there's no sound, it's hard to stand up. Then you start to hear your heart. After some time you may see things that aren't there. Nobody has stayed in this room for more than 45 minutes! A whisper is usually about 15 dB. Normally you can only whisper to people near you. But in St. Paul's Cathedral in London, you can whisper to a friend more than 30 meters away. In the famous Whispering Gallery, the sound goes around the walls to your friend on the other side.

第三章软有多软？ 世界上最安静的地方是哪里？ 是一个没有人也没有车的地方吗？ 北极?在水下走很长的路？ 在美国明尼苏达州的奥菲尔德实验室有一个特殊的房间。 声音在墙壁和地板上的特殊空间里传播，所以没有回声。 墙壁很坚固，所以外面没有声音进来。 那是世界上最安静的地方。 在这个特别的房间里你会感觉不一样。 首先，你可能得坐下来。 没有声音的时候，很难站起来。 然后你开始倾听自己的心声。 一段时间后，你可能会看到不存在的东西。 没有人在这个房间里待过超过45分钟！耳语通常在15分贝左右。 通常你只能对身边的人耳语。 但在伦敦的圣保罗大教堂，你可以和30米外的朋友耳语。 在著名的窃窃私语画廊，声音穿过墙壁传到另一边的朋友那里。

Today, we have electric cars. They are very quiet. Are they too quiet? Most people use their ears when they walk across a street— they don't always look left and right. Electric cars can be a big problem for blind people. When you can't see, you have to listen for cars coming. Some countries say that electric cars must make a noise. So the makers of the cars need to know the best noise, and how loud it needs to be. Is the country quieter than the city? Birds wake up early, and they can be noisy— above 70 dB. But, yes, the country is quieter than a busy city. When some people go and live in the country, they find it's too quiet. Sometimes they can't sleep because the noises are different, or because there's not enough noise. Listening is different from hearing. Sometimes you hear noises without listening to them. There's a noise outside maybe people working. You're not listening to it, but you know it's there. When the noise stops, you look up. Why? Because you want to know why it stopped.

今天，我们有了电动汽车。 他们很安静。他们是不是太安静了？ 大多数人在过马路的时候都会用耳朵——他们并不总是左右看。 电动汽车对盲人来说是个大问题。 当你看不见的时候，你就得听着有没有车开过来。 一些国家说电动汽车必须发出噪音。 因此，汽车制造商需要知道最佳噪音，以及它需要多大的音量。 乡村比城市安静吗？ 鸟类起得很早，它们可能会很吵——超过70分贝。 但是，是的，乡村比繁忙的城市安静。 当一些人去乡下生活时，他们发现那里太安静了。 有时他们睡不着，因为噪音不同，或者因为噪音不够。 听不同于听。 有时你会听到一些声音而不去听。 外面有声音，可能是有人在工作。 你没有在听，但你知道它在那里。 当噪音停止时，你抬头看。 为什么?因为你想知道为什么它停止了。

CHAPTER 4 Do You Need Ears to Hear? WE HAVE ONE MOUTH AND ONE NOSE. WHY DO WE HAVE TWO EARS? You're standing next to a road. You hear a car. You know it's coming from the left because the sound gets to your left ear first. If you are deaf in one ear, it's more difficult to know where a sound is coming from. Do all animals hear in the same way? Bats hear with their ears, but they also send out a high sound with their mouth or nose. When this sound hits something, echoes come back. The bat now knows where the thing is and how big it is. We call this echolocation. Some people use echolocation, too. Daniel Kish is blind. He takes other blind people for walks. He knows where to go because he makes noises and listens to the echoes. Because of these echoes, he knows what's near him. For example, he knows if there are trees close to him. Daniel teaches other blind people how to use echolocation to do things. With this skill, blind people can walk more easily and can also play some games.

第四章你需要耳朵倾听吗？ 我们有一张嘴和一鼻子。 为什么我们有两只耳朵？你站在路边。 你听到了汽车的声音。你知道它是从左边来的，因为声音先传到你的左耳。 如果你一只耳朵聋了，就很难知道声音是从哪里来的。 所有动物的听觉都是一样的吗？ 蝙蝠用耳朵听声音，但它们也用嘴或鼻子发出很高的声音。 当这个声音碰到什么东西时，回声就会回来。 蝙蝠现在知道那个东西在哪里，它有多大。 我们称之为回声定位。 有些人也使用回声定位。 丹尼尔·基什是盲人。他带其他盲人去散步。 他知道要去哪里，因为他会发出声音，并倾听回声。 因为这些回声，他知道附近有什么。 例如，他知道附近是否有树。 丹尼尔教其他盲人如何使用回声定位来做事。 有了这项技能，盲人可以更轻松地行走，也可以玩一些游戏。