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  • General

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  • 超声超声

    A smiling dolphin alongside a yawning bat, illustrating their common use of ultrasound.

    What could this smiling dolphin and yawning bat possibly have in common? It’s not just that both of them are mammals. Both of them also use ultrasound to find things in the dark.
    ::这些笑笑的海豚和哈欠蝙蝠有什么共同之处? 不仅仅是它们都是哺乳动物。 它们都使用超声波在黑暗中找到东西。

    What Is Ultrasound?
    ::什么是超声波?

    Ultrasound is sound that has a higher than the human ear can detect. It includes all sound with wave frequencies higher than 20,000 waves per second, or 20,000 hertz (Hz). Although we can’t hear ultrasound, it is very useful to humans and some other animals. Uses of ultrasound include echolocation, sonar , and ultrasonography.
    ::超声波是超声波,其声音比人类耳能探测到的要高。 它包括波频率每秒超过20,000波或20,000赫兹(Hz)的所有声音。 虽然我们听不到超声波,但它对人类和其他动物非常有用。 超声波的使用包括回声定位、声纳和超声波摄影。

    Echolocation
    ::异同定位

    Animals such as bats and dolphins send out ultrasound waves and use their echoes, or reflected waves, to identify the locations of objects they cannot see. This is called echolocation. Animals use echolocation to find prey and avoid running into objects in the dark. You can see in the Figure  how a bat uses echolocation to find insect prey. 
    ::蝙蝠和海豚等动物发出超声波,使用回声,或反射波,以确定它们看不见的物体的位置。这称为回声定位。动物使用回声定位寻找猎物,避免在黑暗中跑到物体中。您可以从图中看到蝙蝠如何利用回声定位寻找昆虫猎物。

    A bat emits ultrasound waves in a wave pattern to locate insect prey.

    Sonar
    ::声纳

    Sonar uses ultrasound in a way that is similar to echolocation. Sonar stands for so und na vigation and r anging. It is used to locate underwater objects such as submarines. That’s how the ship pictured in the Figure is using it. A sonar device is both a sender and a receiver. It sends out ultrasound waves and detects the waves after they reflect from underwater objects. 
    ::声纳使用超声波的方式与回声定位相似。 声纳代表声波导航和测距。 它用于定位海底等水下物体。 图中描绘的船舶就是这样使用的。 声纳装置既是发送器,又是接收器。 它发出超声波,在从水下物体反射后检测波。

    A ship using sonar to detect a submarine beneath the water's surface.

    The to underwater objects can be calculated from the known of sound in water and the time it takes for the to travel to the object. The equation for distance traveled when speed and time are known is:
    ::水下天体可以根据已知的水声和行驶到天体所需的时间计算。当已知速度和时间时,距离的方程式是:

    Distance = Speed × Time

    Consider the ship and submarine pictured in the Figure . If an ultrasound wave travels from the ship to the submarine and back again in 2 seconds, what is the distance from the ship to the submarine? The travels from the ship to the submarine in just 1 second, or half the time it takes to make the round trip. The speed of sound waves through ocean water is 1437 m/s. Therefore, the distance from the ship to the submarine is:
    ::如果超声波在2秒钟内从船舶到潜艇再回回回,离船舶到潜艇的距离是多少?从船舶到潜艇的往返距离只有1秒钟,或是往返航行所需时间的一半。通过海水的声波速度是1437米/秒。因此,从船舶到潜艇的距离是:

    Distance = 1437 m/s × 1 s = 1437 m

    Q: Now assume that the sonar device on the ship sends an ultrasound wave to the bottom of the water. If the sound wave is reflected back to the device in 4 seconds, how deep is the water?
    ::问题:现在假设船上的声纳装置将超声波送入水底。如果音波在4秒后反射回到设备,水的深度是多少?

    A: The time it takes the wave to reach the bottom is 2 seconds. So the distance from the ship to the bottom of the water is:
    ::A:波浪到达底部的时间是2秒。从船到水底的距离是:

    Distance = 1437 m/s × 2 s = 2874 m

    Use the PLIX Interactive below to simulate how echolocation can be used to map the seafloor:  
    ::使用下面的 PLIX 互动模拟如何使用回声定位绘制海底图 :

    Ultrasonography
    ::超超声波

    Another use of ultrasound is to “see” inside the human body. This use of ultrasound is called ultrasonography. Harmless ultrasound waves are sent inside the body, and the reflected waves are used to create an image on a screen. This technology is used to examine internal organs and unborn babies without risk to the patient. You can see a doctor using ultrasound in the Figure . 
    ::超声波的另一个用途是“看”人体内部。超声波的这种使用被称为超声波。超声波被送入体内,反射波被用于在屏幕上生成图像。该技术用于检查内脏和未出生婴儿,而不会危及病人。您可以在图中用超声波看到医生。

    A doctor performs an ultrasound on a pregnant woman, examining an unborn baby.

    Summary
    ::摘要

    • Ultrasound is sound that has a wave frequency higher than the human ear can detect. It includes all sounds with wave frequencies higher than 20,000 waves per second, or 20,000 hertz (Hz).
      ::超声波是波频率高于人类耳能检测到的波频率的声音,包括波频率高于每秒20,000波或20,000赫兹(赫兹)的所有声音。
    • Animals such as bats and dolphins send out ultrasound waves and use their echoes to identify the locations of objects they cannot see. This is called echolocation.
      ::蝙蝠和海豚等动物发出超声波,并用回声识别它们看不见的物体的位置。这被称为回声定位。
    • Sonar stands for sound navigation and ranging. It is used to locate underwater objects such as submarines.
      ::声纳代表健全的导航和测距,用于定位潜水器等水下物体。
    • Ultrasonography is the use of reflected ultrasound waves to “see” inside the body. 
      ::超声波法是使用反射超声波“看”身体内。

    Review
    ::回顾

    1. Define ultrasound.
      ::定义超声波。
    2. Explain how animals use echolocation to find things in the dark.
      ::解释动物如何使用回声定位 在黑暗中找到东西
    3. What does sonar stand for? How is it used to locate underwater objects?
      ::声纳代表什么?它如何用来定位水下物体?
    4. A sonar device on a ship sends ultrasound waves under the water to locate a sunken ship. It takes the ultrasound wave 0.6 seconds to travel from the device to the sunken ship and back again. How far below the surface is the sunken ship?
      ::船舶上的声纳装置在水下发出超声波,以定位沉船。超声波0.6秒后,超声波才能从该装置飞到沉船,然后再返回。沉船在地表下方多远?
    5. How is ultrasonography like sonar?
      ::超声波摄影像声纳怎么样?