How Do Ultrasonic Waves Work?

Ultrasounds are sound waves that have frequencies higher than audible sound. Although its physical properties are the same as audible sound, the only difference is that humans cannot hear these sound waves. The upper audible limit varies a bit from person to person, but is usually around 20 kHz in healthy people. Different ultrasound devices have the ability to operate with frequencies ranging between 20 kHz and several gigahertz. Many people wonder, "How does ultrasonic wave work?" You need to understand a few concepts before you get in a position to clearly understand how these waves actually work.

How Do Ultrasonic Waves Work?

As mentioned already, ultrasound waves come with higher frequencies than audible sound waves, but it is also important to understand that these ultrasonic waves have shorter wavelengths. It means the distance between one ultrasonic wave entering your ear and the one following that one is much shorter as compared to normal sound waves. These features make ultrasound quite effective in many different fields.

Ultrasonic devices can detect objects and measure distances as well. Similarly, ultrasound imaging is used on a large scale in medicine. Not only this, it is used for everything from industrial drilling to welding and producing photographic film to homogenized milk. How do ultrasonic waves work in different fields? Here is a bit more for your understanding.

1. Navigate and Locate

Ultrasonic waves are used in ships, not only for navigation but also for locating objects underwater. These sound waves travel a lot faster through water than air. Submarines make use of these types of sound waves and use it for a type of navigation called sonar, which is more like underwater radar.

The sonar system works by sending out sound waves and then listening for the echoes. The system then times how long it takes for the echoes to come back. This helps figure out if there are other submarines, ships or obstacles nearby.

2. Apply to Side-Scan Sonar

Different sonar systems make use of different sound frequencies. They may use low infrasound, audible sound, or very high ultrasound. Side-scan sonar usually uses high-frequency sounds. The system comes with a scanning unit called a towfish, which is dragged behind a ship and made to produce wide sonar beams to either side. These beams leave at angles and then reflect back again. This type of sonar system proves quite effective in marine archeology, plain-old fishing, and ocean research. As different fish reflect sound differently, the sonar helps identify different types of fish. It is usually important to use sound with higher frequencies to get more detail.

3. Help Nondestructive Testing

How do ultrasonic waves work in nondestructive testing? It actually makes use of ultrasonic echolocation to get information about mechanical structures. When there is a change in the material, there will be an impedance mismatch after an ultrasonic wave reflects from it. That is why ultrasonic testing can help to identify holes, faults, corrosion or cracks in materials, to determine the quality of concrete, to inspect welds, and to monitor metal fatigue. Using the same principle, ultrasonic waves may prove helpful when inspecting structures in nuclear reactors.

4. Apply to Ultrasonic Cleaning

High-intensity ultrasonic waves are now used in a variety of applications, and ultrasonic cleaning is among the most popular. The process involves setting up ultrasonic vibrations in liquid tanks in which different objects are placed already for cleaning. Ultrasonic vibration and cavitation of the liquid by the waves create turbulence in the liquid and triggers the cleaning action.

Ultrasonic cleaning has become quite popular today and is used with items such as surgical instruments, dentures, and small machinery. Ultrasonic cleaning also helps enhance degreasing. Most ultrasonic equipment uses the high-intensity vibrations of a transducer, which helps to move a machine tool. Sometimes, diamond tools are also used for better performance.

5. Catalyze Chemical or Electronic Reaction

Ultrasonic waves can produce chemical effects mainly by creating an electrical discharge as a result of the cavitation process. That is the reason why ultrasound is now used as a catalyst in some chemical reactions, including reduction, oxidation, polymerization, hydrolysis, molecular rearrangement and deploymerization. It is possible to complete chemical processes more rapidly by making the right use of ultrasound.

6. Apply to Ultrasound Scanning

X-rays are still used largely for medical diagnostic imaging because these rays have high photon energies, but ultrasound scanning is fast catching up. X-rays may be poplar but they are highly ionizing, which means they can destroy molecular bonds in the body tissue. This makes ultrasound a better choice – it is a mechanical vibration, so is not an ionizing form of energy. In sensitive cases where the use of x-rays may prove damaging, the use of ultrasonic waves is preferred.

How do ultrasonic waves work for diagnostic medical imaging? It works on the same principle as sonar – a piezoelectric transducer is used to produce high-frequency ultrasound waves, which encounter change in acoustic impedance as they pass through internal organs and as a result, produce reflections. It is also possible to get information about different internal organs by considering the time and amount of delaying of the various reflections. Different types of techniques are usually used during ultrasonic scanning, depending on the types of transducers used – the most common techniques are the B-scan mode, the A-scan technique, and the M-scan mode.

7. Assist Therapy and Surgery

When well-focused at high frequencies, ultrasonic waves can be used to create internal heating of tissue. It can be done without affecting nearby tissue, which is why the technique proves effective in relieving pains in joints, especially in the shoulder and back. Scientists are currently making use of ultrasonic waves to devise a better treatment for some specific types of cancer. They believe that focusing ultrasonic waves can heat the tumor without affecting surrounding tissue, which may work great in cancer treatment.

What's more, ultrasonic waves are used in trackless surgery, which is a form of surgery that does not require any incision. Focused ultrasound has already been in use to treat Parkinson's disease by forming brain lesions in those areas that have previously been inaccessible through surgery. Ultrasonic waves also work effectively to destroy kidney stones. Moreover, ultrasound waves are used during pregnancy to gather information about the fetus.

How do ultrasonic waves work for pregnant women? Check out the following video to learn more:

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