问题 单项选择题

人耳能听得到的音频信号的频率范围是20 Hz~20 kHz,包括语音、音乐和其它声音,其中语音频率范围通常为______。

A.小于20 Hz

B.300~3400 Hz

C.300 Hz~20 kHz

D.高于20 kHz

答案

参考答案:B

解析:PC机上处理的音频信号主要是人耳能听得到的音频信号,其范围为20 Hz~ 20 kHz,包括三类:
(1)语音:也称话音,指人的说话声,频率范围通常为300~3400 Hz;
(2)音乐:由乐器演奏出的声音,频率范围通常为20 Hz~20 kHz;
(3)其它声音,如风声、雷鸣等,频率范围通常为20 Hz~20 kHz。
频率小于20 Hz的声波称为次音信号或亚音信号或次声波,高于20 kHz的信号称为超声波。

阅读理解
King's College Summer School
King's College Summer School is an annual( 每年的) training program for high school students at all levels who want to improve their English. Courses are given by the teachers of King's College and other colleges in New York. Trips to museums and culture centers are also organized. This year's summer school will be from July 25 to August 15.
More information is as follows:
Application (申请) date
l Students in New York should send their applications before July 18, 2012.
l Students of other cities should send their applications before July 16, 2012
l Foreign students should send their applications before July 10, 2012
Coursesl English Language
Spoken English: 22 hours
Reading and Writing: 10 hours
l American History: 16 hours
l American Culture: 16 hours
Stepsl A letter of self-introduction
l A letter of recommendation(推荐)
﹡ The letters should be written in English with all the necessary information.
Costl Daily lessons: $200
l Sports and activities: $100
l Travels: $200
l Hotel service: $400
﹡You may choose to live with your friends or relatives in the same city.
Please write to:
Thompson, Sanders
1026 King' s Street
New York, NY 10016, USA
E-mail: KC-Summer-School@ yahoo, com
小题1:50. You can most probably read the text in ________.
A.a newspaperB.a travel guide
C.a textbookD.a telephone book
小题2:51. Which of the following is true about King' s College Summer School?
A.Only top students can take part in the program.
B.King' s College Summer School is run every other year.
C.Visits to museums and culture centers are part of the program.
D.Only the teachers of King' s College give courses.
小题3:52. If you are to live with your relatives in New York, you will have to pay the school __
A.$200B.$400C.$500D.$900
小题4:53. What information can you get from the text?
A.The program will last two months.
B.You can write to Thompson only in English.
C.As a Chinese student, you can send your application on July 14, 2012
D.You can get in touch with the school by e-mail or by telephone.
多项选择题