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 approximately$20\mathrm{Hz}$to$20,000\mathrm{Hz}$, which nearly always decays with age. Sounds with a lower frequency than$20\mathrm{Hz}$are infrasound, while sounds above$20,000\mathrm{Hz}$are 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.

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
  • Check for defects in materials

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:

$d=\frac{vt}{2}$,

where$d$is distance,$v$is wave speed$(\mathrm{m}/\mathrm{s})$, and$t$is time$\left(\mathrm{s}\right)$. 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.

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.

Using ultrasound to create an image of a baby in the womb, commons.wikimedia

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.

Industrial use of ultrasound to test for defects such as cracks, StudySmarter Originals