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 approximatelyto, which nearly always decays with age. Sounds with a lower frequency thanare infrasound, while sounds aboveare 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.
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Jetzt kostenlos anmeldenSound 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 approximatelyto, which nearly always decays with age. Sounds with a lower frequency thanare infrasound, while sounds aboveare 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.
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:
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:
,
whereis distance,is wave speed, andis time. 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 about. 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!
Question 1
A research vessel has discovered an old shipwreck resting on the seabed using sonar. It did this using an ultrasound pulse, which tookfor the echo to return. If the speed of sound in water is, calculate the depth of the shipwreck.
Answer 1
It takes the ultrasound pulseto 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.
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:
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.
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.
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.
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 onlyseconds, while others return later atseconds. The speed of sound in the metal is. 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 wavesto travel to the defect, reflect off it and then return to the receiver. Therefore, the time of the wave's journey is halved toto reach the defect.
It takes the remaining ultrasound wavesto 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 toto reach the end of the metal.
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.
Ultrasound can be used to vibrate particles, dislodging unwanted 'dirt' particles.
Metal tools and objects such as castings, bolts, or pipes can be tested for internal cracks or defects using ultrasound.
Ultrasound is useful in foetal scans, assessing the health of internal organs, and treating specific diseases.
Major uses of ultrasound are in navigation, cleaning, medicine, and industry.
What is the approximate range of human hearing?
20Hz to 20,000Hz
What are sounds with frequencies below the range of human hearing called?
Infrasound
What are sounds with frequencies above the range of human hearing called?
Ultrasound
Which of these is not a use of ultrasound?
Detecting and measuring the size of Earthquakes
What is the approximate speed of sound in water?
1500m/s
Which method is used to detect objects underwater and detect defects in industrial materials?
Echo sounding
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