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声音是由物体的振动引起的,人靠声带的振动来說話,風琴靠風琴管中空气柱的振动而发出各种音响,……不論从那里发出的声音,都是一种彈性波,可以在介质(气体、液体或固体)中傳播,通常叫声波。声波頻率在20—20,000赫芝范圍內,人耳能够听到;高于20,000赫芝的,人耳就听不到了,叫做超声。超声的用途实在多得很,工厂用它来探測厚鋼板深处的細微缺陷,潜艇利用它查明海底的群山和暗礁,医院用它为患者解除痛苦……超声的用途,可以写成一大本专著。
The sound is caused by the vibration of the object. The person speaks by the vibration of the vocal cords. The organ sounds by the vibration of the air column in the organ pipe. No matter what the sound is from it, it is an elastic wave. Medium (gas, liquid, or solid), usually called sound waves. Sound waves in the range of 20-20,000 Hertz can be heard by human ears, and those above 20,000 Hertz can’t be heard by human ears. They are called ultrasound. The use of ultrasound is very versatile. The factory uses it to detect subtle defects in the depths of thick steel plates. The submarine uses it to find out the mountains and reefs on the sea floor. The hospital uses it to relieve the suffering of patients... The use of ultrasound can be written as a large one. This monograph.