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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.
According to paragraph 5, a scientist recently visiting the Peruvian rain forest discovered that________.
选项 A、the specialized frequencies of the sounds made by animals are determined by their body size
B、the frequencies of sounds made by animals at night are generally random
C、animals and insects of particular species make sounds at specific frequencies
D、animal and insect calls differ depending on whether they are heard in the laboratory or outside in nature
答案C
解析 本题是事实信息题，问根据第5段，到秘鲁的雨林的科学家发现了什么。第5段第4句即科学家在实验室分析录音后的发现——每种动物和昆虫都有自己特定的频率。C项“特定种类的动物和昆虫会发出特定频率的声音”与此说法相符，故选。A项“动物发出的特定声音频率由它们的体型大小决定”出自第5段首句。此句并非该科学家发现的内容，原文从第2句才开始提到去秘鲁雨林中的科学家，故排除A项。B项“动物们在夜间发出的声音频率是随机的”和文中第3句表达的意思相矛盾，该句说的是这些夜间的声音其实是非常有秩序的。D项“动物和昆虫的叫声在实验室里和在自然界会有所不同”，该段讲的是科学家到自然界中录音，再把录音带带回实验室得到的发现，并没有将实验对象室内室外的不同发音进行对比，该项属于无中生有。
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