The Ultrasonic transducer is a type of device used to convert other types of energy into ultrasonic vibration. There are many basic types, classified by energy source and wave-forming medium. Mechanical devices include gas-driven or pneumatic sensors, such as whistles and their liquid-driven sensors, such as hydrodynamic oscillators and vibrating blades. This equipment is limited to low ultrasonic frequencies and has many industrial applications including drying, ultrasonic cleaning and fuel injection into burners. Electromechanical transducers are widely used, including piezoelectric and magnetostrictive devices. A magnetostrictive transducer uses a magnetic material in which an oscillating magnetic field is added to squeeze the atoms of the material together to produce periodic changes in the length of the material, resulting in high-frequency mechanical vibrations. Magnetostrictive transducers are mainly used in low frequency range, and are commonly used in ultrasonic cleaning machines and ultrasonic processing applications.

By far the most popular and commonly used Ultrasonic transducer are piezoelectric crystals, which convert the oscillating electric fields on the crystals into mechanical vibrations. Piezoelectric crystals include quartz, Rochelle salts, and other types of ceramics. Piezoelectric transducers tend to be used in the full frequency range and at all output levels. The ability to select a particular style for a particular application. For example, a disc gives a flat ultrasonic wave, while bending the radiation surface into a slightly concave or bowl shape also produces an ultrasonic wave that focuses at a certain point.

Piezoelectric and magnetostrictive transducers also act as ultrasonic signal receivers, receiving ultrasonic vibrations and converting them into electrical oscillations.