If an external force acts on an elastic medium such as a gas, a liquid or a solid, an undulating propagation of pressure and density fluctuation occurs in space and time, starting from the point where the force is applied. This known as sound.
Ultrasound is the term used when the frequency of the propagating wave exceeds 16,000 Hz, making it undetectable for the human ear. The frequency range for ultrasound is up to 16 GHz, i.e., 16 billion cycles per second.
Industry, medical technology and research use ultrasound for many purposes. The best known field of application is sonography, also known as echography. Here, ultrasound is used to generate images of tissue and organs. The great advantage of sonography over other imaging methods in medical technology is that sound waves are harmless and can even be used for unborn babies.
In addition to medical imaging, low sound intensities are also required for applications in measurement technology. The intensity of the sound describes the power that hits a certain surface. If this exceeds 10 W/cm2, it is referred to as high-power sound. In contrast to low-power ultrasound, high-power ultrasound causes material changes or even destruction and is therefore suitable for use in material processing, ultrasonic cleaning or in the medical field in >> Lithotripsy.