Filtering a lot outuh the way a sophisticated radar

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filtering a lot out—uh, the way a sophisticated radar system can ignore echoes from stationary objects on the ground. Radar does this to remove “ground clutter”—information about, um, hills or buildings that it doesn’t need … but bats—we thought they were filtering out this kind of information because they simply couldn’t analyze it. But it looks as if we were wrong. Recently, there was this experiment with trees and a specific species of bats—a bat called the lesser spear-nosed bat. Now a tree should be a huge acoustical challenge for a bat, right? I mean, it’s got all kinds of surfaces, with different shapes and angles … So, well, the echoes from a tree are going to be a mass of chaotic acoustic reflections, right? Not like the echo from a moth. So, we thought, for a long time, that bats stopped their evaluation at simply “that’s a tree.” Yet, it turns out that-that bats, or at least this particular species, can not only tell that it’s a tree, but can also distinguish between, say, a pine tree and a deciduous tree—like, a maple, or an oak tree … just by their leaves—an-and when I say “leaves,” I mean pine needles, too. Any ideas on how it would know that? Male Student Well … like with the moth—could it be their shape? Professor You’re on the right track. It’s actually the echo off all the leaves—as a whole— that matters. Now, think: A pine tree—with all those little, densely packed needles … those produce a large number of faint reflections in what’s called a “smooth” echo—the waveform is very even … but an oak —which has fewer but bigger leaves with stronger reflections—produces a jagged waveform—or what we call a “rough” echo. And these bats can distinguish between the two—and not just with trees, but with any echo that comes in a smooth or rough shape. APPENDIX B
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TOEFL iBT ® Quick Prep 34 Transcript for Track 4: Narrator Listen again to part of the lecture. Then answer the question. Professor Now, before I go on, let me just respond to something Carol was saying—this idea that bats are blind … Narrator Why does the professor say this? Professor Now, before I go on, let me just respond to something Carol was saying … APPENDIX B
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TOEFL iBT ® Quick Prep 35 APPENDIX B Listening Practice Set 3: Transcript for Track 5: Narrator Listen to part of a lecture in a history class. Professor So we’ve been talking about the printing press, how it changed people’s lives, making books more accessible to everyone. More books meant more reading, right? But as you know, not everyone has perfect vision. This increase in literacy, in reading, led to an increase in demand for eyeglasses. And here’s something you probably haven’t thought of: This increased demand impacted societal attitudes towards eyeglasses. But, um, first let me back up a bit and talk about vision correction before the printing press. And what did people with poor vision do—I mean especially those few people who were actually literate—what did they do before glasses were invented? Well, they had different ways of dealing with not seeing well. If you think about it, poor vision wasn’t their only problem. I mean, think about the conditions
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