四 川 建 筑 职 业 技 术 学 院 授 课 教 案 Text B Sounds We Cannot Hear I. Introduction 1. Introductory Remarks Are there any sounds we cannot hear? Yes. But does it mean there is something wrong with our hearing? As a matter of fact, most of us can only hear the sound vibrations that occur within the range of 20 times per second to 20 000 times per second. Those below and above the limits are the sounds we cannot hear. The vibrations that are too slow to be heard are infra-sound or subsonic sound(亚声); while those fast vibrations are called ultrasonic sound or supersonic sound(超声). So far people have known a lot about ultrasonic sound and its wide applications; however, the infra-sound is something new to us. The passage you are going to read will give you something about this kind of sound. 2. Introductory Questions Exercise 1 Exercise 3 after reading the passage II. Outline A. The Arizona highway accident and its possible causes (Para. 1) B. Infra-sound -- a possible killer with the effects similar to drunkenness (Para. 2) C. Study of Infra-sound (Paras. 3 - 4) 1. Destructive effect producer 2. Valuable information provider D. The Conclusion (Para. 5) A useful yet dangerous sound III. Detailed Study of the Text 1. Suddenly he starts to drift across to the other side of the road. -- Suddenly he starts to drive off its own way and go toward the other side of the road. drift: to be carried along by wind, waves, or currents e.g. The boat drifted down the river. We switched off the motor and started to drift along. 2. An oncoming truck flashes its headlights and hoots furiously, but to no avail. -- A truck coming towards the car gives signals by flashing its headlights and sounding its hom, but with no result. to no avail: of no use; with no result e.g. We tried and tried, but it was all to no avail. He tried to persuade him to come, but to no avail. 3. There is a sickening crash; the truck ends up half off the road ... -- Suddenly there is a loud horrible sound; as a result the truck is knocked almost outside the road... crash: 1) a sudden, loud sound made by a violent fall, blow or break e.g. a crash of breaking glass 2) a violent vehicle accident e.g. His father was killed in a car crash. end up: to come to be in a particular state, or finish in a particular way; arrive in a place one did not plan to go e.g. If you don't eat less, you'll end up looking like a whale! We set off for Newcastle, but ended up in Scotland. 4. The Arizona highway police, who arrive on the scene shortly afterwards, immediately ask all the obvious questions. -- The Arizona highway police soon come to the place where the traffic accident has happened and at once ask the routine questions. shortly afterwards: very soon; before long e.g. The president of Russia, who arrived in China shortly afterwards, immediately held talks with his Chinese counterpart. 5. ....it was a mild autumn day. -- ... it was a pleasantly warm autumn day. mild: not very cold; not hard or causing much discomfort or suffering; slight e.g. The coat is too heavy for such a mild day. The thief was given a milder punishment than he deserved. 6. As far as the police could tell, the car had been in good mechanical condition. -- The police believed that the car had never been mechanically out of order. as far as one can/could tell/know/remember: used to say that one thinks that something is true, although he/she does not know all the facts, can't remember completely, etc. e.g. As far as I can tell, the whole thing should cost about $ 500. So far as I know, they're coming by car. in (good) condition: in a good state; in good health, physically fit e.g. Everything arrived in good condition. If you spare half an hour for exercise every day, you'll soon be back in good condition. 7. There was one thing, though: it was a new car ... -- However, there was one thing worthy of note: it was a new car. though: but; nevertheless e.g. It is a hard job. I enjoy it, though. What you said was true but it was ,though, unkind. 8. Infra-sound is sound that the human ear cannot hear, as it cannot pick up vibrations below about thirty cycles a second (or above about 22 000). -- The human ear cannot hear infra-sound as it is unable to hear vibrations below about thirty cycles a second (or above about 22 000 cycles a second.) pick up: to be able to hear or receive e.g. We picked up radio signals for help from the damaged plane. cf. Where did you pick up your English? (= learn) The system looks difficult at first, but you'll soon pick it up. (= begin to understand it) 9. A motor vehicle running steadily at speed produces audible sound, but it also produces 四 川 建 筑 职 业 技 术 学 院 授 课 教 案 infra-sound, -- A motor vehicle being kept driving fast makes sounds we cannot hear in addition to sounds we can hear, ... vehicle: a machine such as a bus, car, that carries people or things from place to place e.g. No vehicles are permitted inside the park. at speed: at high speed; fast e.g. When we're traveling at speed, the passing countryside just seems a blur. It's dangerous to go round corners at speed. 10 ....depending on the car, the road surface and the person concerned ... --... decided by the car, the road surface and the person involved... Note that when "concerned" is used after a noun, pronoun, or a noun phrase, it means "involved". e.g. I'd like to thank everyone concerned for making the occasion run so smoothly. It was quite a shock for all concerned. (= everyone involved) 11. You can become literally "drunk with sound". -- "Drunk with sound" being a metaphor, the whole sentence means that too much infra-sound can really make you unable to judge in a sound way. cf. drunk with sth.: behaving in a strange, often unpleasant way because of the excitement of something e.g. drunk with power/success literally: used for giving force to an already strong and esp. metaphorical expression e.g. She was literally blue with cold. He was literally blazing with anger. 12. He wanted to investigate low frequency sound, ... -- He wanted to make a good study of low-frequency sound .... investigate: to examine the reasons for (something), the character of (someone), etc. e.g. The police are investigating the causes of a railway accident. Scientists are investigating how the crash occurred. 13. He therefore built a huge copy of a police whistle ... -- So he made a whistle which looked like a police whistle but was much larger ... 14 .... the operator who switched it on dropped dead on the spot. -- ... the worker died on the ground of the test site immediately after he turned on the power. switch on: to turn (an electric light or apparatus) on by means of a switch e.g. The TV set doesn't work. Have you switched it on? on the spot: 1) at the place of the action e.g. They know what's going on because they are on the spot. 2) at once e.g. He was hit on the head and died on the spot. 15 .... that his internal organs had been reduced to a jelly by the low-frequency vibrations. 四 川 建 筑 职 业 技 术 学 院 授 课 教 案 -- that the low-frequency vibrations turned the inside parts of his body into a jelly, reduce (sth./sb.) to sth.: to cause (something or someone) to reach (a certain condition);make(something) smaller or less e.g. Allied bombing reduced the city to ruins. I reduced the problem to a few simple questions. If you are to give a talk, try to reduce your ideas to a few notes, so that you can speak freely from your notes rather than read out the whole speech. 16. Low-frequency vibrations can be detected several minutes before an earthquake. -- Low-frequency vibrations can be measured / noticed a few minutes before an earthquake occurs. detect: to find out; notice e.g. These instruments can detect minute amounts of radiation. Small quantities of poison was detected in the dead man's stomach. 17. People who live in earthquake zones are aware that dogs often start to howl before an earthquake, ... -- People who live in areas liable to earthquakes know that dogs often begin to howl before an earth-quake .... (un)aware (of): (not) having knowledge or consciousness (of something) e.g. He seemed to be (un)aware of the trouble he was causing. He was completely (un)aware that be was being watched. 18. Water is particularly sensitive to low frequency vibrations, ... -- Water is especially easily influenced by low frequency vibrations .... be sensitive to: to be strongly or easily influenced or changed by something e.g. She is so weak that she is extremely sensitive to cold. cf. He's very sensitive to his students' need for encouragement and knows when to praise them. (= knowing or being conscious of the feelings and opinions of others) 19. The Japanese, ... are familiar with this phenomenon, ... -- The Japanese ... clearly know/have a good knowledge of this kind of phenomenon .... be familiar with: to have a thorough knowledge (of) e.g. I am not familiar enough with the computer. We are already fairly familiar with each other. 20 .... it is time to look for a safe place well away from a large building. --... people should find a safe place which is very far away from a large building. 21. It has even been claimed that some animals become aware of earth tremors as much as several hours before they are observed by human beings, and that rabbits and deer have been seen running in terror from what afterwards turns out to be the epicentre of an earthquake. -- Some people have even claimed that some animals are able to sense the shaking of the earth several hours before human beings detect it, and they also claimed that the place from which terrified rabbits and deer have been seen running is proved to be the very centre of an earthquake. 四 川 建 筑 职 业 技 术 学 院 授 课 教 案 turn out: happen to be, or be found to be e.g. The party turned out a success. To our surprise, the stranger turned out to be an old friend of my mother's. 22. More research will be needed before we are sure how infra-sound can be used. -- It is necessary for us to do more research in order to make sure that we can make good use of the infra-sound. 23 .... the information it provides may be vital, ... -- ... the information the infra-sound gives may be of great importance .... "it" here refers to the "infra-sound" in the previous sentence. vital: extremely important and necessary for something to succeed or exist e.g. Choosing the right equipment is vital. If you are to avoid being blamed, it is vital that you should tell them the truth at once. IV. Summary of the Text A running vehicle makes infra-sound at between ten and twenty cycles per second which we cannot hear, but it can affect us because it can produce "euphoria, recklessness, lower efficiency and dizziness." Professor Gavreau of Marseilles in his experiment discovered that infra-sound is extremely dangerous to the body. However, by detecting low-frequency vibrations, we can foretell the coming of an earthquake. So we need more research on how infra-sound can be used and how we can protect ourselves from being hurt by it. Text-related Information 1. Arizona: (AZ) a state in the southwest of the USA known for its desert climate 2. infra-sound: Dangerous, destructive and harmful sound waves whose frequency is lower than 20 Hz and not audible to human ears post-mortem (examination): autopsy, an examination of a dead body, esp. by cutting it open, to discover the cause of death