托福TPO27 Lecture2

Lecture2-History of Musical Instruments (Violins) Narrator Listen to part of a lecture in a history of musical instruments class. Professor So musical instruments evolved in ways that optimize their acoustical properties, how the instrument vibrates and sends those vibration through the air to our eardrums. Now professional musicians are very particular about their instruments, they want instruments that help them fully express the intent of the composer, which of course translates into a more enjoyable listening experience for the audience members. Yet most audience members probably aren’t even aware of how much the instrument matters. I mean, OK. Think about the last concert you attended. When you applauded, what went through your mind? Student I recently heard a violinist who totally blew me away. So when I applauded, I guess I was showing my appreciation for his skill, the hours of practicing he must have put in. Professor And his violin? Student Didn’t really think about it. It looked exactly like mine, which is inspiring in a way knowing my violin could also produce beautiful tones, that maybe I would sound that good someday. Professor I hope you do. But if your violin isn’t as good as his… Student You mean he might not sound as good playing my violin? Professor As I said, tone quality differs from instrument to instrument. The question is why. Why does one instrument sound more beautiful than another, even if they look identical? There’s a particularly interesting case with an extraordinary generation of violins made in Northern Italy, in the city of Cremona, back in the late 1600s - early 1700s. These vintage Cremonese violins are considered the best in the world. But it’s not like the makers of those violins were any more skilled than their modern-day counterparts. They weren’t. Today’s top violin makers can pretty much replicate all the physical attributes of a Cremonese violin. But it’s generally thought that the acoustical quality of modern violins doesn’t live up to the quality of the vintage ones. Student So what attributes of the old violins have been replicated? Professor Oh, their dimensions, shape, their fingerboard height, uh, general craftsmanship. For a long time, people thought the varnish used to coat and protect the violins was special. But research showed it was the same ordinary varnish used on furniture. However, researchers have discovered that there are something special about the wood the violins were made from. And recently they have been able to replicate that too. Student How? Unless the trees that Cremonese used are still alive. Professor The trees weren’t replicated, just the wood, specifically the wood’s density. Density is determined by how trees grow. Trees, old trees that don’t grow in the tropics grow seasonally, they grow faster early in the year in the springtime than they do later in the year. So early growth wood is relatively porous. Late growth wood is denser, less porous. And this variation shows up in the trees growth rings. The denser layers are generally darker than the less dense layers. We call this variation the density differential. Variations in wood density affect vibrations, and therefore, sound. When scientists first analyzed the wood of vintage Cremonese violins in compared with the modern violin wood, they calculated the average density and found no difference. Later, other researchers measured the density differential and found a significant difference. Modern violins had a greater variation, a larger differential. Student So you mean the density of the wood in the Cremonese violins is, is more uniform? Professor Correct. Student But Northern Italy isn’t in the tropics. Professor No. But climate matters. Turns out the Cremonese violins were made from trees that grew during a Little Ice Age, a period when temperatures across Europe were significantly lower than normal. So the trees grew more evenly throughout the year, making the density differential relatively small. Student But you said someone replicated the Cremonese wood. Professor The density differential was replicated. Student What did they do? Try to simulate an Ice Age climate in their greenhouse and grow some trees in there? Professor No, what happened was a material scientist figured out a way to process wood to make it acoustically similar to the Cremonese wood. He basically exposed the wood to a species of fungus, uh, a mushroom. In the forest, fungi are decomposers. They break down dead wood. But this particular fungus nibbles away only at certain layers in the wood, leaving other layers alone. As a result, the density differential of the fungi-treated wood approach that of the Cremonese wood.