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| 文章出处：学生大考试站 发布时间：2005-10-12 |
eristics: pitch, loudness, and quality or timbre (音色). As was indicated above, pitch is determined largely by the frequency of the wave reaching the ear. The higher the frequency the higher is the pitch. Loudness depends on the amplitude (振幅)of the wave reaching the ear. For a given frequency, the greater the amplitude of the wave the louder the sound. To discuss quality of sound we need to clarify the concept of overtones. Sounds are produced by vibrate at one definite frequency producing a pure tone. This is the way a tuning fork is usually used. When objects vibrate freely after a force is momentarily applied, they are said to produce their natural frequency. Some objects, like strings and air columns, can vibrate naturally at more than one frequency at a time. The lowest frequency which an object can produce when vibrating freely is known as the object's fundamental frequency; other frequencies that the object can produce are known as its overtones. The quality of a sound depends on the number and relative amplitude of the overtones present in the wave reaching the ear.
6. The main purpose of the passage is to .
A. show the impossibility of hearing sounds above 20,000Hz
B. define the nature and quality of musical sounds
C. analyze what gives a work of art its musical quality
D. explain the applications of ultrasonic frequencies
7. The style and content of this passage indicates that it is most likely an excerpt from .
A. a proposal by an innovative composer of modern music
B. an informal article written for a popular magazine
C. a scholarly monograph on aesthetics
D. a college textbook on music theory
8. According to the author, the timbre of a musical sound is dependent on .
A. speed
B. amplitude
C. frequency
D. overtones
9. According to the passage ultrasonic frequencies are
A. unhearable
B. excessively
C. characterized by a great amplitude
D. less than 20,000 Hz
10. Which of the following individuals would most likely use terms like Mach 5 or Mach 9?
A. a helicopter pilot.
B. a musician
C. an astronaut
D. a submarine navigator
Passage 3
Both Mercy Warren and Abigail Adams admired Catherine Macaulay, the radical author of A History of England, who supported the cause of the American patriots. Under Macaulay's influence Mercy Warren conceived her plan to write a history of the A
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