NARRATOR:Listen to part of a lecture in a music history class.The professor has been discussing music of the twentieth century.
MALE PROFESSOR:And what instrument comes to mind when you think of rock and roll?
FEMALE STUDENT:The electric guitar?
MALE PROFESSOR:Exactly. I think it's fair to say that the sound of the electric guitar typifies the rock-and-roll genre, which became popular in the 1950s.But really, the instrument we know today was the result of a continuing development that started, for all practical purposes, in the 1920s.But long before that even, people were experimenting with ways to modify traditional acoustic guitars.The first guitars were wooden-this is the Spanish guitar-and the strings were made from animal products.Then came steel strings, and that led to the lap guitar-which is also called the steel guitar because the player slides a steel rod up and down the neck.And those are all acoustic guitars, OK?But then, eventually, we have electric guitars.Over the years, many inventors and musicians contributed to the design of these instruments, and each design was intended to alter the sound in some way-at first, at least with the electric guitar, to make it louder.
[Slight pause to get back to chronology] Eh, so let's get back to when the steel guitar was first introduced in the United States.It was right after the Spanish-American War...in the late 1890s.U.S. sailors who were stationed in Hawaii,[brief aside] then a U.S. territory, were very enamored with the music they heard there; uh, Hawaiian music was based on the steel guitar I just described.Some sailors learned how to play the steel guitar and brought it home to the States.Before long, Hawaiian steel guitar music was all the rage in the mainland U.S.It actually had a strong influence on the development of several musical genres-rock and roll, most notably, but also jazz and blues.
Anyway... by the 1920s, with the advent of the public dance movement, people were gathering in large groups to listen to steel-guitar music.But they had trouble hearing it, especially in large, public settings.As I mentioned, the instrument was played horizontally, on the lap. Since the strings faced upward, the sound was projected toward the ceiling rather than outward toward the audience.Something had to be done because the music venues and the audiences kept getting larger and larger.So, what would you do?
MALE STUDENT:Find a way to amplify the sound?
MALE PROFESSOR:Yes. And to do that, inventors started attaching electronic devices-electrical coils-to acoustic guitars. And the electronics worked!But attaching electronics didn't just affect how loudly you could play; it also changed the quality of the sound.These early electric guitars were hollow, and these early amplifiers caused vibrations in the bodies of the instruments.So, as the sound got louder, it became more distorted.Fuzzy sounding.And what musicians at the time wanted was a pure, clean sound.
MALE STUDENT:So, where does Les Paul fit in? Wasn't he the first to electrify acoustic guitars?
MALE PROFESSOR:Uh, no. Electrified guitars already existed by the time Les Paul came into the picture, around 1940.
What Paul did was experiment with ways of removing the distortions. And he succeeded! [lowly]He designed a guitar with a solid body that relied solely on electronics.Paul's solid body eliminated the vibrations, and thus, the distortions.
FEMALE STUDENT:Excuse me, but when I think of electric guitar music, I think of Jimi Hendrix.
MALE PROFESSOR:Jimi Hendrix, one of my favorites!
FEMALE STUDENT:But Hendrix's style really was all about distortion. That's what's so great about his music-all those special effects.I think a lot of rock-and-roll fans preferred that to a pure sound.
MALE PROFESSOR:Yeah, you're getting ahead of me here...but good! Because the point I was gonna make is that the sound of rock and roll changed over the years, and the designs and technology of electric guitars made those changes possible.
So whereas Les Paul's goal was to remove the distortion, later musicians wanted to produce it.And by the time Jimi Hendrix came around...Well, essentially, Hendrix reinvented the electric guitar-in the sense that he created amazing effects and vibrations that changed the sound of rock and roll completely.So, eventually, people tried to improve on Les Paul's model, [to be diplomatic] well, to modify it, I should say.
原文定位：Professor: And what instrument comes to mind when you think of rock ‘n’ roll?
Student: The electric Guitar?
Professor: Exactly. I think it’s fair to say that the sound of the electric guitar typifies the rock ‘n’ roll genre, which became popular in the 1950s.But really the instrument we know today was the result of a continuing development that started for our practical purposes in the 1920s.
教授一开始提问引出关键信息 electric Guitar，后面的 but 转折提到了continuing development.。