A Ultrasonic transducer is a device that converts some other type of energy into ultrasonic vibrations. There are several basic types, classified by energy source and wave-producing medium. Mechanical devices include gas-driven or pneumatic sensors, such as whistles, and liquid-driven sensors, such as hydrodynamic oscillators and vibrating blades. These devices are limited to low ultrasonic frequencies and have many industrial applications, including drying, ultrasonic cleaning, and fuel injection into burners. Electromechanical transducers are used in a much wider range of applications, including piezoelectric and magnetostrictive devices. A magnetostrictive transducer utilizes a magnetic material in which an oscillating magnetic field is applied to squeeze the atoms of the material together, resulting in periodic changes in the length of the material, thus generating high-frequency mechanical vibrations. Magnetostrictive transducer is mainly used in lower frequency range, commonly used in ultrasonic cleaner and ultrasonic processing applications.