首页
登录
职称英语
The range in frequencies of musical sounds is approximately 20-20,000 cycles
The range in frequencies of musical sounds is approximately 20-20,000 cycles
游客
2025-05-06
8
管理
问题
The range in frequencies of musical sounds is approximately 20-20,000 cycles per second (cy/sec). Some people can hear higher frequencies khan others. Longitudinal waves whose frequencies are higher than those within the audible range are called ultrasonic frequencies. Ultrasonic frequencies are used in sonar for such purposes as submarine detection and depth finding. Ultrasonic frequencies are also being tried for sterilizing food since these frequencies kill some bacteria. Sound waves of all frequencies in the audible range travel at the same speed in the same medium. In the audible range, the higher the frequency of the sound the higher is the pitch. The term supersonic refers to speed greater than sound. An airplane traveling at supersonic speed is moving at a speed greater than the speed of sound in air at that temperature. Mach 1 means a speed equal to that of sound. Mach 2 means a speed equal to twice that of sound, etc.
Musical sounds have three basic characteristics: pitch, loudness, and quality or timbre. 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 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 vibrating objects. If these objects are given a gentle push, they usually 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. [br] Ultrasonic frequencies are ______.
选项
A、inaudible
B、excessively fast
C、characterized by a great amplitude
D、death rays
答案
A
解析
超声频率是听不见的。答案可以在第一段找到。作者说,其频率远远大于可以听见的音域的纵波被称为超声频率。这说明,超声繁率是听不见的。
转载请注明原文地址:https://tihaiku.com/zcyy/4064933.html
相关试题推荐
Therangeinfrequenciesofmusicalsoundsisapproximately20-20,000cycles
Therangeinfrequenciesofmusicalsoundsisapproximately20-20,000cycles
Therangeinfrequenciesofmusicalsoundsisapproximately20-20,000cycles
Therangeinfrequenciesofmusicalsoundsisapproximately20-20,000cycles
Thoughherparents______hermusicalability,Jerrilou’spianoplayingisreall
Asa______actor,hecanperform,sing,danceandplayseveralkindsofmusical
Thecomposerssoonbegantowritemusicaldramas______aboutBiblestoriesinc
Evidencecameup______specificspeechsoundsarerecognizedbybabiesasyoung
Thecomposerssoonbegantowritemusicaldramas______aboutBiblestoriesinch
随机试题
Managementjargoncanalienatestaffandleavebosseslookinguntrustworthy
多层建筑物二层以上楼层按其外墙结构外围水平面积计算建筑面积,层高在2.20m及以
编码的运算符号中,用于将同一表格或不同表格中的编码联合在一起,以表示两个或两个以
男性,36岁,大面积烧伤8h,已静脉输液3000ml,判断其血容量是否补足的简便
消费金融公司的客户定位为()。A.高收入者 B.城乡居民 C.低收入者
建设项目信息管理中,对于信息的表述形式正确的是()。A:情报 B:声音 C
引起疱疹性咽峡炎的病毒是()。A.腺病毒 B.合胞病毒 C.副流感病毒
关于招标公告或资格预审公告,下列说法不正确的是()。A、进行资格预审的公开招标项
“老年丧失期观”认为老年期丧失的内容包括()。(2009-11)A:身心健康
关于紫金锭的叙述,错误的是A.功能为辟瘟解毒,消肿止痛 B.含雄黄、朱砂,孕妇
最新回复
(
0
)