It is based on the principle of transmitting acoustic waves into water and recording the time interval between the emission and return of a pulse; The resulting time of flight, together with knowledge of the speed of sound to water, allows the distance between the sonar and the target to be determined. This information is typically used for navigation purposes or to obtain depths for charting purposes. The distance is measured by multiplying half the time from the signal's output pulse to its return by the speed of sound to the water, which is approximately 1.5 kilometers per second [T÷2×(4700 feet per second or 1.5 kilo per second)]. The first practical fatometer was invented by Herbert Grove Dorsey and patented in 1928.

Medical ultrasound transducers (probes) come in a variety of different shapes and sizes for use in making cross-sectional images of various parts of the body. The transducer can be used in contact with the skin, such as in fetal ultrasound, or inserted into a body opening such as the rectum or vagina. Doctors performing ultrasound-guided procedures typically use a probe positioning system to hold the ultrasound transducer.[7]​.

Compared to other medical imaging modalities, ultrasound has several advantages. It provides real-time imaging, is portable, and therefore can be carried at the bedside. It has a substantially lower cost than other imaging strategies and does not use harmful ionizing radiation. Drawbacks include several limits on its field of view, the need for patient cooperation, dependence on the patient's physique, difficulty in imaging structures obscured by bone, air, or gases, and the need for a qualified operator, usually with professional training. Because of these drawbacks, novel implementations of portable ultrasound are gaining popularity. These miniature devices continuously monitor vital signs and alert to the appearance of early signs of abnormality.[8]​[9]​.

Ultrasonic sensors can detect the movement of targets and measure their distance to many automated factories and process plants. Sensors can have a digital output enabled or disabled to detect the movement of objects or an analog output proportional to distance. They can detect the edge of the material as part of a web guidance system.

Ultrasonic sensors are widely used in cars as parking sensors to help the driver reversing into parking spaces. They are being tested for other automotive uses, such as ultrasonic person detection and assisting in autonomous UAV navigation.

Since ultrasonic sensors use sound instead of light for detection, they work in applications where photoelectric sensors do not work. Ultrasonics are a great solution for detecting clear objects and measuring the level of liquids, applications that photoelectrics struggle with because of the translucency of the target. Additionally, target color or reflectivity do not affect ultrasonic sensors, which can operate reliably in bright environments.

Passive ultrasonic sensors can be used to detect high-pressure gas or liquid leaks, or other hazardous conditions that generate ultrasonic sound. In these devices, the audio from the transducer (microphone) is converted to the range of human hearing.

High-power ultrasonic emitters are used in commercially available ultrasonic cleaning devices. An ultrasound transducer is placed in a stainless steel pan that is filled with a solvent (often water or isopropanol). An electrical square wave feeds the transducer, creating a sound in the solvent loud enough to cause cavitation.

Ultrasonic technology has been used for multiple cleaning purposes. One of them that has gained good traction over the last decade is ultrasonic gun cleaning.

Ultrasonic testing is also widely used in metallurgy and engineering to evaluate corrosion, welds, and material defects using different types of scans.

Ultrasonic transducers convert AC to ultrasound, as well as vice versa. Ultrasound, usually refers to piezoelectric transducers or capacitive transducers. Piezoelectric crystals change size and shape when a voltage is applied "Strain (electricity)" ; The AC voltage makes them oscillate at the same frequency and produce ultrasonic sound. Capacitive transducers use electrostatic fields between a conductive diaphragm and a support plate.

The beam pattern of a transducer can be determined by the area and shape of the active transducer, the wavelength of the ultrasound, and the speed of sound of the propagating medium. The diagrams show the sound fields of an unfocused and a focused ultrasonic transducer in water, clearly at different energy levels.

Since piezoelectric materials generate a voltage when applied strongly, they can also function as ultrasonic detectors. Some systems use separate transmitters and receivers, while others combine both functions in a single piezoelectric transceiver.

Ultrasonic transmitters can also use non-piezoelectric principles. like magnetostriction. Materials with this property change size slightly when exposed to a magnetic field and make practical transducers.

A condenser ("condenser") microphone has a thin diaphragm that responds to ultrasound waves. Changes in the electric field between the diaphragm and a widely spaced support plate convert sound signals into electrical currents, which can be amplified.

The diaphragm (or membrane) principle is also used in relatively new micromachined ultrasonic transducers (MUT). These devices are manufactured using silicon micromachining technology (MEMS technology), which is especially useful for manufacturing transducer arrays. Diaphragm vibration can be measured or induced electronically using the capacitance between the diaphragm and a widely spaced support plate (CMUT), or by adding a thin layer of piezoelectric material to the diaphragm (PMUT). Alternatively, recent research has shown that diaphragm vibration can be measured using a small optical ring resonator embedded within the diaphragm (OMUS).[3]​[4]​.

Ultrasonic transducers are also used in acoustic levitation.[5]​.

It is based on the principle of transmitting acoustic waves into water and recording the time interval between the emission and return of a pulse; The resulting time of flight, together with knowledge of the speed of sound to water, allows the distance between the sonar and the target to be determined. This information is typically used for navigation purposes or to obtain depths for charting purposes. The distance is measured by multiplying half the time from the signal's output pulse to its return by the speed of sound to the water, which is approximately 1.5 kilometers per second [T÷2×(4700 feet per second or 1.5 kilo per second)]. The first practical fatometer was invented by Herbert Grove Dorsey and patented in 1928.

Medical ultrasound transducers (probes) come in a variety of different shapes and sizes for use in making cross-sectional images of various parts of the body. The transducer can be used in contact with the skin, such as in fetal ultrasound, or inserted into a body opening such as the rectum or vagina. Doctors performing ultrasound-guided procedures typically use a probe positioning system to hold the ultrasound transducer.[7]​.

Compared to other medical imaging modalities, ultrasound has several advantages. It provides real-time imaging, is portable, and therefore can be carried at the bedside. It has a substantially lower cost than other imaging strategies and does not use harmful ionizing radiation. Drawbacks include several limits on its field of view, the need for patient cooperation, dependence on the patient's physique, difficulty in imaging structures obscured by bone, air, or gases, and the need for a qualified operator, usually with professional training. Because of these drawbacks, novel implementations of portable ultrasound are gaining popularity. These miniature devices continuously monitor vital signs and alert to the appearance of early signs of abnormality.[8]​[9]​.

Ultrasonic sensors can detect the movement of targets and measure their distance to many automated factories and process plants. Sensors can have a digital output enabled or disabled to detect the movement of objects or an analog output proportional to distance. They can detect the edge of the material as part of a web guidance system.

Ultrasonic sensors are widely used in cars as parking sensors to help the driver reversing into parking spaces. They are being tested for other automotive uses, such as ultrasonic person detection and assisting in autonomous UAV navigation.

Since ultrasonic sensors use sound instead of light for detection, they work in applications where photoelectric sensors do not work. Ultrasonics are a great solution for detecting clear objects and measuring the level of liquids, applications that photoelectrics struggle with because of the translucency of the target. Additionally, target color or reflectivity do not affect ultrasonic sensors, which can operate reliably in bright environments.

Passive ultrasonic sensors can be used to detect high-pressure gas or liquid leaks, or other hazardous conditions that generate ultrasonic sound. In these devices, the audio from the transducer (microphone) is converted to the range of human hearing.

High-power ultrasonic emitters are used in commercially available ultrasonic cleaning devices. An ultrasound transducer is placed in a stainless steel pan that is filled with a solvent (often water or isopropanol). An electrical square wave feeds the transducer, creating a sound in the solvent loud enough to cause cavitation.

Ultrasonic technology has been used for multiple cleaning purposes. One of them that has gained good traction over the last decade is ultrasonic gun cleaning.

Ultrasonic testing is also widely used in metallurgy and engineering to evaluate corrosion, welds, and material defects using different types of scans.