Applications of Ultrasound

Sound is made by the vibration of particles, but there are sounds that we can't hear. A lot of them actually! Humans have a hearing range of approximately20 Hzto20,000 Hz, which nearly always decays with age. Sounds with a lower frequency than20 Hzare infrasound, while sounds above20,000 Hzare considered to be ultrasound. Animals such as bats, dogs, and dolphins have superior hearing to us and can hear frequencies that humans can't. However, we humans have come up with many ingenious uses for ultrasound frequencies, even though we can't hear them ourselves. This article will investigate and discuss some of the most common and useful real-world applications of ultrasound.

Applications of Ultrasound Applications of Ultrasound

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Table of contents

    Examples of ultrasound application

    There are four broad ways in which ultrasound can be utilised in real-life applications. Ultrasound can be used for navigation, cleaning, in the medical field and in industry. Some of the many applications of ultrasound to be discussed in this article are listed below:

    • Navigation
      • Measure distances underwater
    • Cleaning
      • Jewellery, antiques, and clockwork
      • Removing tartar and plaque from teeth
    • Medical
      • Foetal ultrasound scans
      • Assess the health of internal organs
      • Treat joint pain, tumours, and kidney stones
    • Industrial

    Navigation application of ultrasound

    Navigating the depths of Earth's seas and oceans is extremely important for fishing ships, submarines, and research vessels. Unfortunately, light waves are heavily distorted when crossing the boundary of air to water and they cannot penetrate very far below the surface. To help compensate for this problem we utilise SONAR (Sound Navigation And Ranging) and a process called echo sounding.

    High-frequency ultrasound waves can be used to detect objects in deep water and to measure the water's depths. For instance, a fishing trawler will transmit an ultrasound pulse to determine the distance to the seabed. This pulse will eventually echo, meaning the sound will be reflected from the seabed. This echo will then be detected from the trawler. The time taken for the ultrasound pulse to return to the vessel can be used alongside the wave speed to calculate the depth of the water as follows:


    wheredis distance,vis wave speed(m/s), andtis time(s). Note that the factor of two is there because the wave travels twice the distance between the trawler and the seabed, just like what happens with echolocation. Therefore, the distance travelled by the wave is halved to calculate the actual distance to the seabed.

    The wave speed of sound in water is about1500 m/s. However, the exact speed can vary by small amounts. This is based on several factors, such as the water's temperature, its salinity (salt content) and the water pressure. All of these variables change depending on the time of day, the season and the depth of the water. Thankfully, in this article, we will take the wave speed to be constant!

    Applications of Ultrasound Diagram showing how echo sounding works StudySmarter

    Echo sounding, commons.wikimedia

    Question 1

    A research vessel has discovered an old shipwreck resting on the seabed using sonar. It did this using an ultrasound pulse, which took3.6 sfor the echo to return. If the speed of sound in water is1500 m/s, calculate the depth of the shipwreck.

    Answer 1

    It takes the ultrasound pulse3.6 sto travel to the shipwreck, reflect off it and then return to the research vessel. Now, use the modified distance equals to the product of speed and time formula to calculate the depth.

    d=vt2 1500 m/s × 3.6 s2 = 2700 m

    Cleaning applications of ultrasound

    Remember that sound is caused by the vibration of particles. More vibrations per second means a higher frequency of sound. Jewellers use ultrasound to help clean their jewellery. They use a device to emit ultrasound waves at their dirty products. This causes the particles inside the jewellery to vibrate very quickly, which shakes the dirt apart. This technique is also commonly used when cleaning antique clockwork, which can become delicate from age.

    The hygienists at your local dental practice use a similar technique on your teeth to remove plaque and tartar. Hygienists prefer to use ultrasound devices over old-fashioned manual scraping instruments for several reasons:

    • Patients report greater comfort during dental procedures.
    • The tips of the smaller ultrasound tools can more easily reach areas where manual tools would have more trouble.
    • Safety for those with weaker teeth, such as seniors. No scraping force is required when using ultrasound tools, which might accidentally remove precious enamel and leave teeth more sensitive and vulnerable to decay.

    Medical field applications of ultrasound

    You might already be aware that we use ultrasound equipment as diagnostic tools to monitor a baby's development in their mother's uterus. An ultrasound transducer is placed on the skin, which can both transmit and receive ultrasound waves. Some of the ultrasound waves are reflected at solid boundaries, such as the foetus's bones, muscles, or tissues and then returned to the transducer. A computer can then generate an image using the data from the ultrasound scan. This is a process called ultrasound imaging.

    Applications of Ultrasound A fetal ultrasound and an illustration of how it works StudySmarterUsing ultrasound to create an image of a baby in the womb, commons.wikimedia

    An X-ray scan would actually generate a much clearer image of a developing foetus than an ultrasound. Unfortunately, X-ray radiation has very high energies, which could seriously impact the health of the unborn baby, causing birth defects or learning disabilities. Foetuses are very vulnerable to radiation as they only possess relatively few cells that divide rapidly. They also have little protection from radiation, except from their mother's abdomen.

    Similarly, abdominal ultrasounds can be performed to assess the health of the internal organs within your abdomen. This includes the liver, pancreas, spleen, and gallbladder. There are other medical applications of ultrasound technology too. For example, treating joint pain and certain types of tumours. Ultrasound can also be used to eliminate painful kidney or bladder stones. To destroy these stones, surgeons pass thousands of high energy ultrasound waves through the body to break the stones down into smaller pieces. These smaller stones can then move through the urinary tract safely and then be excreted from the body.

    Industrial applications of ultrasound and crack detection in metals

    Ultrasound waves are also very useful in industrial applications. The tools and materials we use mustn't be defective. To help accomplish this, we use ultrasound waves to check for cracks inside metal objects, such as castings, bolts, or pipes. After an ultrasound wave enters a material it is usually reflected back at the boundary of the far side of the object. However, if the metal object has an invisible defect such as a crack inside the material, then the ultrasound wave will reflect off the crack instead. The reflected ultrasound wave will return to the receiver in less time than predicted, which will inform the people testing the material that it is defective. The speed of the wave inside the material will be constant, so the distance between the ultrasound source and the defect can be calculated using echo sounding.

    Applications of Ultrasound Diagram showing the crack detection in metals application of ultrasound StudySmarterIndustrial use of ultrasound to test for defects such as cracks, StudySmarter Originals

    Question 2

    Kelly is testing a large piece of metal using ultrasound to determine if it has any defects. Some of the transmitted ultrasound waves are reflected earlier than the rest. Some waves return to the receiver after only0.004seconds, while others return later at0.01seconds. The speed of sound in the metal is2000 m/s. Calculate the distance between the ultrasound source and the material's defect, then calculate the distance between the ultrasound source and the end of the metal.

    Answer 2

    It takes the ultrasound waves0.004 sto travel to the defect, reflect off it and then return to the receiver. Therefore, the time of the wave's journey is halved to0.002 sto reach the defect.

    d = vt 2000 m/s × 0.002 s = 4 m

    It takes the remaining ultrasound waves0.010 sto travel to the end of the metal, reflect off it and then return to the receiver. Therefore, the time of the wave's journey is halved to0.005 sto reach the end of the metal.

    d = vt 2000 m/s × 0.005 s = 10 m

    Applications of Ultrasound - Key takeaways

    • Ultrasound is sound waves with frequencies higher than the normal range of human hearing, above20,000 Hz.
    • Echo sounding is a useful technique for determining distance. An ultrasound pulse is transmitted, reflected at an object or boundary, then returned to a receiver. The time taken can be used to help calculate the distance.
    • Navigation application: We use ultrasound waves and echo sounding to help navigate and detect objects underwater.
    • Cleaning application: Ultrasound waves can be used to clean dirty jewellery and other delicate objects, as well as to clean teeth.
    • Medical application: The development of babies in their mother's womb can be monitored with ultrasound scans. Other uses include treating joint pain, and tumours, or eliminating kidney and bladder stones.
    • Crack detection in metals application: Ultrasound waves can be used to detect defects hidden deep within materials such as metals. The sound echoing technique is used to locate any defects such as cracks.
    Frequently Asked Questions about Applications of Ultrasound

    How is ultrasound applied in navigation? 

    Ultrasound is used in navigation, by echo sounding. By emitting an ultrasound pulse, it is possible to determine the distance to another object as the pulse is reflected back to the source. By timing how long the ultrasound pulse takes to return, the distance can be calculated.

    How is ultrasound applied in cleaning? 

    Ultrasound can be used to vibrate particles, dislodging unwanted 'dirt' particles.

    What is an example of crack detection in metals?

    Metal tools and objects such as castings, bolts, or pipes can be tested for internal cracks or defects using ultrasound.

    Which area of the medical field is ultrasound applied? 

    Ultrasound is useful in foetal scans, assessing the health of internal organs, and treating specific diseases.

    What are the major uses of ultrasound? 

    Major uses of ultrasound are in navigation, cleaning, medicine, and industry.

    Test your knowledge with multiple choice flashcards

    What is the approximate range of human hearing?

    What are sounds with frequencies below the range of human hearing called?

    What are sounds with frequencies above the range of human hearing called?

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