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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 6, what did the research of Professor Krause indicate about sounds in rain forests?
选项 A、Older rain forests have more varied sound frequencies than younger rain forests.
B、The patterns of sounds in rain forests are consistent over time.
C、The speed of sound movement can be affected by the location of the rain forest.
D、It is difficult to distinguish the atmospheric sound patterns of rain forests in one region from those in another.
答案B
解析 本题是推论题，问伯纳德.克劳斯教授的研究中表明了关于热带雨林声音的什么信息。第6段第2句为克劳斯教授的研究结论，该结论论证了声音系统的稳定性，这与B项“随着时间的推移，雨林中的声音模型是不变的”相符。A项“苍老的雨林比新生的雨林有更加多样的音频”和C项“声音传播的速度受雨林所处位置的影响”在文中均无相关信息。D项“很难区分不同地区雨林空气中的声音模型”的意思是不同地区雨林的声音模型具有相似性，这有悖于文中教授的研究发现，即不同地区有自己独特的声音模型，故排除D项。
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