TPO 29
Section1
Conversation1
Narrator
Listen to part of a conversation between a student and an employee at the registrar’s office.
Employee
Morning. How can I help you?
Student
Well, I am kind of confused about my schedule. I printed it out this morning. But one of the classes I registered for is missing.
Employee
OK. Let’s see if we can figure this out. What’s your name?
Student
Lisa Johnson.
Employee
Alright. I am bringing up your schedule on the computer. Hmmm…It looks like you’re registered for Introduction to Astronomy, Survey of American Literature, and Introduction to Government and Politics.
Student
Well, yes, but I also registered for a language class—Level One Japanese. Did they…I don’t know, maybe cancel it?
Employee
I doubt it. The Japanese classes are quite popular. But let’s take a look at the list of Japanese classes being offered this semester just to make sure. Um… what section did you register for?
Student
I don’t remember the section number. But it’s the one that meets at eleven.
Employee
Ah! That would be section five. Well, according to this, the class is completely full. Are you sure…you, um, you registered online, right?
Student
Yeah.
Employee
Did you get a confirmation message?
Student
What do you mean?
Employee
Well, once you’ve successfully registered for a class, the computer gives you a message saying you are in.
Student
Oh. You mean that message at the bottom of the screen that says you’re now registered for this class? Actually, I didn’t get that message. I got one that said “instructor’s signature required.” I thought I just needed to get to professor’s signature on the first day of class.
Employee
Well, you do. But the professor might no sign it. It depends on how full the class is and how many additional students the professor is willing to let in.
Student
So that means I am not registered for the class. Not unless the professor signs me in. What, uh, what should I do now?
Employee
Let me give you the form the professor needs to sign. Go to the class on the first day, get there early, so you can talk to the professor before class starts. Find out if he or she is willing to let you in. If so, bring the signed form back here and we’ll register you for the class.
If not, well, you’ll have to find a different class. I’d start looking for alternatives now, just in case.
Student
What do you think my chances are of getting into this class?
Employee
Students often add and drop classes once the semester begins, so there is a real chance a seat would open up. But of course there are no guarantees.
Student
It’s just that I need a language course to graduate and that’s the only Japanese class that fits my schedule.
Employee
Yes. But according to our records, you are only in your first year here. If you can’t take the class this semester, you still got time.
Student
I know. I was just hoping to take care of my requirements earlier rather than later.
Employee
I understand. I just wanted to make sure you know you had options.
Lecture1-Ecology(Pedodiversity)
Narrator
Listen to part of a lecture in a plant ecology class.
Professor
So far we have covered biodiversity in the hard wood forest here in the upper peninsula of Michigan from a number of angles. We’ve looked at everything from how biodiversity relates to species stability, to competition for forests resources and more.
But now I want to discuss what’s called pedodiversity. Pedodiversity is basically soil diversity. When we analyze pedodiversity within an area, we are measuring how much variability there is in soil properties and how many different types of soil there are in a particular area.
So we look at soil chemistry. For example, how much nitrogen or magnesium there’s in the soil in one spot. And we compare it with the chemistry of the soil a short distance away.
Until recently, there hasn’t been a whole lot of attention paid to pedodiversity. But that’s changing rapidly. More and more studies are being done in these fields. There’s a link between biodiversity and pedodiversity, an obvious relationship between soils and flora and fauna, which is why pedodiversity really should be considered in forest management.
A high degree of soil variability in a small area is common, particularly within forests. If you compare soils from a forest with soils that don’t come from a forest, the amount of variability will most likely be greater in the forest’s soil. It generally has more diversity.
Um…OK. There are three main causes of pedodiversity within old-growth forest here in our region of Michigan.
One is tree species. Different species have different influences on soil formation and soil properties. For example, pine trees drop pine needles. And those needles add a lot of acid to the soil. The organic litter of another tree species might add less acid but more of something else. A lot of different types of trees in an area might mean more pedodiversity.
Another cause? Gaps … created when trees fall. You see, where there are gaps, open areas in the forest, the soil there changes. Um… for instance, without a tree to absorb radiation from the Sun, to offer shade, the full intensity of that radiation reaches the ground. The soil where the tree used to be heats up. And without a tree to soak up moisture from the ground, the soil remains wetter than in the surrounding forest. With a higher temperature and more moist conditions, the process of organic matter decomposition speeds up. In other words, organic matter gets broken down and added into the soil more quickly in these gaps than in the surrounding forest.
OK. And the third cause—trees being uprooted. When a tree is uprooted, it might fall into some other trees on its way down, thus falling only partway over. Or it might crash all the way down to the forest floor. Either way, if its roots are pulled up from out of the ground as the tree topples over, then there’s usually a big hole, a pit left in the ground where the roots used to be. And there’s still a lot of soil attached to the roots, clinging to the roots. As that soil is eventually shed from the roots by rain and wind and the movement of squirrels climbing around, things like that. Um... as the soil is shed, it drops down and forms a little hill of dirt, a mound.
Pits and mounds have significantly different soil properties than other areas in the forest. You get a redistribution and mixing of soil as deep roots are ripped up from the ground. Rock fragments can be pulled up too, if they’ve gotten entangled with the roots over the years. So rock fragments from the subsoil can end up concentrated on the surface.
There are forests management implications I want to point out. Forests management impacts soil quality. And when we better understand pedodiversity, we will be better able to predict the impact of forest management on soil. But in general, for positive impact, forest management practices should mimic natural forest processes. And the goal should be to promote pedodiversity, and through this, biodiversity in general.
I have a handout, an article on pedodiversity in a section of forests near here. I want you to read it, because it makes a point that I’ve only touched on. From what I have been saying about the causes of pedodiversity, you might assume that the relationship between forest dynamics, what happens to the trees, and pedodiversity is a one-way street. As the article explains, forest dynamics affects pedodiversity. But pedodiversity also affects forest dynamics. It’s worth bearing in mind.
Lecture2-Architecture(Reverberation)
Narrator
Listen to part of a lecture in an architecture class.
Professor
Today I’d like to talk a bit about the relationship between the built world and sound. Uh, the design of buildings like concert halls or theaters. So, what’s the most important aspect in the design of such a building?
Student
Acoustics?
Professor
Yes. Now, people have been concerned about how sound carries in auditoriums and theaters for at least 2,000 years. But it was not until the beginning of the twentieth century that architectural acoustics became a scientific field. That was when the physicist Wallace Sabine started to do extensive studies on reverberation.
Sabine wanted to find out why the audience could not understand speakers at a lecture hall in Boston. He designed a series of studies on reverberation to figure it out. So, what is reverberation? It’s the persistence of sound in a room after the source has stopped making sound. You see, sound made in a room reflects off the walls, floors and ceiling. That’s the reverberant sound. The time it takes for the reverberant sound to die down is important for the acoustic quality of a room. Sabine recognized this and he came up with an equation to measure a room’s reverberation time.
So, what happens if the reverberation time is very long?
Student
Wouldn’t it be difficult to hear new sounds if you can still hear the old sounds?
Professor
Exactly. A long reverberation time may cause musical notes to drown one another out.
On the other hand, if the reverberation time is very short … meaning, the reverberations are absorbed very quickly, the room is called dead. Performers would feel they have to struggle to fill the room with sound. We don’t want that. In a concert hall or theater, we prefer a live room, where the sound has fullness.
So we need to control the reverberation time. After all, we don’t want the listeners or the performers have to struggle, right?
So what are some important considerations when we design a theater or a concert hall?
Student
The size of the place?
Professor
Absolutely. The larger the room, the longer the reverberation time. So we’ll have to take into account what the room will be mainly used for, since music requires more reverberation than speech. A room intended for music needs to be designed differently from a room intended for drama. For music, we need a very large room, a concert hall, actually I should say for full orchestras. Because for a single instrument, say something like a piano recital, a room with a short reverberation time is better. So for a solo piano a smaller room works well. Yes?
Student
I read that concert halls designed for symphony orchestras have too much echo for jazz music.
Professor
That doesn’t surprise me. Most small jazz groups would need rooms with a shorter reverberation time.
But besides the size of the room, another variable affecting reverberation is the shape of the room. Let’s say you design a rectangular box-like space with bare walls and ceiling, this would allow the sound to act like a ball in a racquetball court, you know, bouncing around and hitting some parts of the walls and ceiling but missing many others. If that happens in a concert hall, audience members may hear some sounds, but not others.
So what can be done to distribute the sound evenly in every direction? The answer is: avoid straight, parallel walls.
Karen?
Student
But I think I’ve seen photos of rectangular concert halls.
Professor
Right. Older concert halls from the 1800s are generally rectangular. But they all have a lot of decorations on the walls inside, lots of ornamental plasterwork like statues, which distribute sound very efficiently, reflecting it in all different directions.
And that brings me to another variable we need to consider. The acoustic characteristics of the building materials as well as the wall and floor coverings. In fact, most objects you see in a concert hall or theater serve double duty. The plush chairs absorb sound and soften reverberation. And the beautiful crystal Chandeliers? They are very good at diffusing sound. You see, everything must be planned down to the last detail in order to predict the acoustic performance of a room.
That being said, there’s something that can’t be controlled by the architect. The audience has an effect on acoustics too. The heads of people are good diffusers of sound. And Architects try to account for this effect in their design, but they can’t guarantee a full auditorium.
Section2
Conversation2
Narrator
Listen to a conversation between a student and his music history professor.
Student
Um, professor Jenkins. The listening journal you assigned us to keep for the Intro to World Music class, well, I am not sure I understand what to do. I listened to the pieces you assigned this week more than once, but when I tried to write about them, I didn’t know what to say.
Professor
Well, it’s not easy to write about music, even for people who are supposedly expert at it.
Student
That makes me feel a little better. But I am just not familiar with how you keep a listening journal. I’ve kept journals for other classes, summarizing and writing about how I felt about readings.
Professor
Well, a listening journal isn’t all that different, I want you to note your feelings about musical compositions too.
Student
OK. There were pieces I like more than others, but I think you want our comments to be a little more…I don’t know, analytical. Right?
Professor
Well, whether you like a piece or not is important, but you should be able to explain why you like a particular piece and be able to talk about its historical and musical context. Actually, the listening journal is a tool to help you listen to music actively, to think about what you are hearing.
Student
Maybe I am finding it difficult because I am not real familiar with most of the music you assigned. I mean, if it’s hip-hop or something I listen to with my friends…
Professor
Yes, because hip-hop is a form that’s familiar and meaningful to you. But you’ll see as the semester progresses and you start learning more about musical forms, you’ll become a more adept listener. And you’ll start noticing patterns.
Student
OK. So the songs we listened to this week, the …the Canto?
Professor
The Cante jondo . You remember we said it means “deep song” in Andalusian Spanish? Not only because it’s sung in a deep register, but also because it’s a song about deeper or serious matters, certainly not lighthearted.
Student
Really? Hmm…I guess I didn’t catch the double meaning. That’s kind of cool. But anyway, even with the translations you gave us for the lyrics and everything, I don’t know, I could tell it’s sad, but I wasn’t trying to analyze it, from a musical perspective that is.
Professor
OK. So this is what you should do. Go back and listen to the song selection and this time pay attention to the melody, to repetition, to the …
Student
There was plenty of that. Some parts sounded like the same note played over and over again.
Professor
That’s exactly the kind of observation you would record in a listening journal. So, melody repetition, rhythm, how the piece is structured, as well as your reasons for liking or disliking it.
You know what? I thought everyone was clear about this, but you’ve just given me a great idea. I am going to draw up a list of questions everyone should keep in mind when they are writing their journals. Other students may be having the same problem you are having.
Lecture3-Archaeology(Clovis Culture)
Narrator
Listen to part of a lecture in an archaeology class.
Professor
We will be looking at the original settlement of the Americas next, and I’ll spend the next few classes talking about the Clovis people and the two big questions archaeologists have about them.
The two big questions are, when did the Clovis people arrive in the Americas? And of course, were they the first people in the Western hemisphere. And we’ll get to that. But for today, let’s try to get an idea about, well, a question that’s not addressed as much as the others and that’s – what was their culture like? And how do we figure that out?
Now, again, there’s a great debate about when the Clovis people first arrived in the Americas. And I am not like a lot of archaeologists who want to push the number way back, so let’s use a round number and probably a safe number and say 11,000 years ago. The Clovis people were likely settling North America 11,000 years ago. And leave it at that for now.
Now, most of what we know about the Clovis people comes from one of their tools—the Clovis point. When we talk about a point we are referring to a piece of stone that’s worked to a sharp point, in this case probably to be attached to a spear. The Clovis point may be the most analyzed artifact in archaeology. And the point used by Clovis people differs slightly from later points, in the way that the base of the stone is thinned, uh, it’s thinner toward the base, the part that’s attached to the spear. So when one is found, it’s usually not confused with points made by later groups.
Clovis points have been discovered at both hunting grounds and camp sites, which you might expect. But another fascinating place we find them is in Clovis caches. A cache is just something stored or hidden away. It’s also the term for the place where it’s hidden.
The Clovis caches are collections of tools, stone points and other tools made of stone or bone, often at various stages of manufacturing, some were left unfinished. The traditional explanation is that these were emergency supplies, uh, meant to be used at a later time. Since the Clovis people were highly mobile, it’s plausible that they would set up spots along established travel routes where they keep a variety of items. Either so that they wouldn’t have to carry everything with them or so they could save time once they arrived at a site by not having to make stuff from scratch.
But there’s another theory about the caches based on the quality of some of the points we’ve found. You see, the points in some caches differ from other points, from points at Clovis camp sites for example. For one thing, these cache points are quite large, up to twice as large as regular points, so big that you couldn’t attach one to a spear say, and expect to throw the spear accurately over any distance. So what were they for?
Well, it was originally thought that they were unfinished, that someone was working away a point, then had to stop and put it aside in one of these caches to work on later. The problem is: it’s unlikely that a point would have started out as large as the points in these caches, that would be a lot of stone to chip away. A toolmaker starts with a smaller piece. And actually, far from being unfinished, a lot of these points really show excellent craftsmanship and attention to detail. And not just with respect to the skill, but also with respect to the raw material, it seems that cached points are made from the very best pieces of stone.
So we have to ask—could these points have served another purpose? Maybe be they weren’t just tools. Look at it this way. When the Clovis people first arrived in the Americas, they had a lot to learn about their new environment. Over time, they would have begun to recognize some places as special, important for some reason. Maybe there was always water available there. Or the hunting was especially good. So maybe the cache was a way to mark the place as significant.
Lecture4-Structural Engineering(Carbon Nanotubes)
Narrator
Listen to part of a lecture in a structural engineering class.
Professor
Today let’s begin to look at structural engineering in the Space Age. Uh, new problems…new possibilities mean we can think in new ways, find radically different approaches. So let’s consider…uh, well, what would you say is the biggest obstacle today to putting structures, equipment, people …uh, anything really, into space?
Student
Well, the cost, right?
Professor
Exactly. I mean, just taking the space shuttle up and back one time is hugely expensive. Uh, why?
Student
I guess a lot of it is for fuel, right? To…to get the rocket going fast enough.
Professor
OK. Fast enough to…
Student
To escape Earth’s gravity.
Professor
Good. So we are burning up an enormous amount of fuel at every launch just to get the rocket up to what’s known as escape velocity. Now, escape velocity is around 11 kilometers a second, pretty fast. But do we really have to go this fast?
Student
Well, yeah. I mean, how else can you, um…escape? I mean, that’s the whole point of escape velocity, right? Otherwise gravity will pull you back down to the Earth.
Professor
Actually, that’s a common misconception. Escape velocity is simply the speed of an object that’s …uh, let’s say, shot out of a cannon the minimum initial speed so that the object could later escape Earth’s gravity on its own. But that’s just if there’s no additional force being applied. If you keep on supplying force to the object, keep on pushing it upward. It could pull away from Earth’s gravity at any speed.
Student
Even really slow? So you’re saying …like, if you had a ladder tall enough, you could just climb into space?
Professor
Yeah! Uh, well, theoretically. I mean, I can see some practical problems with the ladder example. Uh, like you might get just a little bit tired out after the first few thousand kilometers or so, uh, especially with all the oxygen tanks you’ll have to be hauling up with you.
No. I was thinking more along the lines of an elevator.
Student
Wait! You are serious?
Professor
Sure. An elevator. That’s a new idea to most of us, but in fact it’s been around for over a century. If we could power such an elevator with solar energy, we could simply rise up into space for a fraction of the cost of a trip by rocket or shuttle.
Student
But wait, elevators don’t just rise up. It have (sic ) to hang on some kind of wire or track or something.
Professor
Uh, true. And for decades that’s exactly what’s prevented the idea from being feasible or even just taken seriously. Where do we find the material strong enough yet lightweight enough to act as a cable or track. I mean, we are talking 36,000 kilometers here. And the strain on the cable would be more than most materials could bear.
But a new material developed recently has a tensile strength higher than diamond, yet it’s much more flexible. I am talking about carbon nanotubes.
Student
OK. I’ve read something about carbon nanotubes. They are strong, alright, but aren’t they just very short little cylinders in shape?
Professor
Ah, yes. But these cylinders cling together at a molecular level. You pull out one nanotube or row of nanotubes, and its neighbor’s come with it, and their neighbors, and so on. So you could actually draw out a 36,000-kilometer strand or ribbon of nanotubes stronger than steel, but maybe a thousandth the thickness of a human hair.
Student
OK. Fine. But what’s going to hold this ribbon up and keep it reach enough to support an elevator car?
Professor
Well, we definitely have to anchor it at both ends. So what we need is a really tall tower here on the ground right at the equator and a satellite in geostationary orbit around the Earth. There’s a reason I mentioned that figure of 36,000 kilometers. That’s about how high an object would have to be orbiting straight up from the equator to constantly remain directly above the exact same spot on the rotating planet Earth. So once you are in this geostationary orbit right over the tower, just lower your carbon nanotube cable down from the satellite, tether it to the tower here on Earth. And there you have it!
Student
So you really think this is a possibility? Like, how soon could it happen?
Professor
Well, the science fiction writer Arthur C. Clarke talked about building a space elevator back in the 1970s. And when someone asked him when he thought this idea might become a reality, his reply was, “Probably about fifty years after everybody quits laughing.”