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  3. HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD (1) Scientists have discovered that animals are experts at exploiting weat

HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD (1) Scientists have discovered that animals are experts at exploiting weat

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问题                                             HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD
    (1) Scientists have discovered that animals are experts at exploiting weather conditions and the physical conditions of their environments so that they are heard or not heard, and seen or not seen. The species living in rain forests must engineer their calls to accommodate all of the obstacles, such as leaf cover, that can deflect and degrade the sounds intended for a potential receiver. Over, short, loud bursts of sound tend to be more effective than longer calls at cutting through the dense foliage.
    (2) There is no natural environment on Earth noisier than a virgin rain forest. In the Peruvian rain forest, every species has developed clever or remarkably sophisticated strategies to ensure that its voice is heard. The noise creates a real challenge for the smaller residents, such as male tree crickets, which need to get the attention of females, often from a relatively long distance. Some species of crickets maximize the volume of their calls by chewing a hole in the middle of a leaf to create a sound baffle, similar to a stereo speaker. The leaf functions as a speaker cabinet, with the cricket in the center acting as the speaker.
    (3) A species of tree frog in Borneo has an inventive approach to getting its mating call heard over the noise. Mataphrenella sudana, which is only an inch long, has learned to exploit the sound properties of a water-filled hole in a tree in the same way that a person uses resonance, the intensification and enrichment of a sound by added vibration, in the shower to sing like a professional performer. The frog searches for a suitable hole and then partially submerges itself in the water. Its forte is the ability to adjust the frequency of its call to the size of the hole and play the tree like a musical instrument. As it sits in the hole, it begins vocalizing at different frequencies until it hits the one note that makes the hole and tree resonate.
    (4) The time of day affects how sound travels in any environment, and this fact is not lost on animals and insects. Early morning and late evening produce conditions that allow sound to travel greater distances than during the middle parts of the day. Sound travels best at night, which is why the rain forest is so wonderfully noisy between dusk and dawn. For species that sleep at night, dusk and dawn are their windows of opportunity to get the best resonance and distance out of a signal. This is why animals, especially birds, tend to be more active and noisy in the early morning and late evening. The British call the phenomenon of birds singing in the early morning the dawn chorus. Because of the superior sound conditions, dusk and dawn are the times to conduct the serious business of attracting mates and defending territories. For predators, it is the best time to track down their noisy prey.
    (5) Another way animals and insects ensure that their calls connect with the intended receivers is by developing their own specialized frequencies, which are determined primarily by the size of their bodies. [A] Recently, a scientist visiting the Peruvian rain forest made an audio tape of a little of the night’s music. [B] When he took the tape back to his lab and analyzed it, he discovered that this seemingly chaotic banquet of sound was actually highly ordered. [C] Each animal and insect is tuned to and calling on its own species-specific frequency, in the same way that radio stations use different signals so that many stations can broadcast at the same time. [D]
    (6) Bernard Krause, a professor at the University of Oregon in Eugene, has found that in older tropical rain forests some species, such as the Asian paradise flycatcher, have become so specialized that their voices occupy several niches of the sound spectrum at the same time, thus laying territorial claim to several audio channels. His recordings from undisturbed rain forests around the world demonstrate a remarkable stability in the combined voices of the residents from year to year. The stability of the ambient sound gives each region a unique sound signature, or fingerprint.
An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Animal species in rain forests have developed a series of adaptations to make themselves heard.
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Answer Choices
(A) Scientists have discovered that animals in rain forests adapt the length of their calls to overcome the barriers created by dense plant growth.
(B) Many species of predators in rain forests prefer dawn rather than dusk as the best time to hear and pursue their prey.
(C) Specialized frequencies facilitate sound transmission within species and also create regional sound environments that are highly stable.
(D) Some smaller animals that live in rain forests use special strategies to increase the volume of their calls and the distance that their calls travel.
(E) Because time of day affects how sound travels, many animals restrict their calls to either nighttime, when sound travels best, or dusk and dawn.
(F) Research conducted in the Peruvian rain forest indicates that well-ordered periods of sound alternate with more chaotic sound periods.
选项
答案C,D,E
解析 文章总结题。C项“特定的频率能够促进物种之间的声音传播，也能赋予不同地区非常稳定的声音环境”是对第5段和第6段的整合。D项“一些雨林中比较小型的动物用一些特殊的策略来扩大叫声的音量和声音传播的距离”是对第2段和第3段的整合。E项“因为一天中的不同时刻对声音的传播有影响，许多动物把呜叫调整到声音传播最好的时候——夜间或黄昏和拂晓”概括了第4段的意思。由此可见，C、D、E三项涵盖了本文主体段落的信息要点：A项“科学家们发现雨林里的动物会改变它们的叫声长度来使声音穿越茂密植被造成的障碍”，本文第1段先提出雨林中茂盛的植被对动物传播声音会造成障碍，第2—5段又讲了动物们增强声音传播效果的四种方法。但是，这四种方法并不包括改变声音的长度，故排除A项。B项“比起黄昏时分，雨林中的许多捕食者偏向以拂晓为听辨和追踪猎物的最佳时机”，该选项对应的是文中第4段最后两句，但是原文说的是黄昏和拂晓都是最佳时机，没有将二者进行比较，故B项错误。F项“针对秘鲁雨林的研究表明，秩序井然的声音时期和比较嘈杂的声音时期交替出现”，该选项对应的是文章第6段第2、3句，但原文表达的意思足，雨林的声音具有很强的稳定性(remarkable stability)，F项与原文矛盾。
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