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Ultrasound is sound with frequencies greater than 20 kilohertz. [1] This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz.
Due to the wide range of signal properties and media they propagate through, specialized equipment may be required instead of the usual microphone, such as a hydrophone (for underwater sounds), detectors of ultrasound (very high-frequency sounds) or infrasound (very low-frequency sounds), or a laser vibrometer (substrate-borne vibrational signals).
Ultrasound energy, simply known as ultrasound, is a type of mechanical energy called sound characterized by vibrating or moving particles within a medium. Ultrasound is distinguished by vibrations with a frequency greater than 20,000 Hz, compared to audible sounds that humans typically hear with frequencies between 20 and 20,000 Hz.
Ultrasonic hearing is a recognised auditory effect which allows humans to perceive sounds of a much higher frequency than would ordinarily be audible using the inner ear, usually by stimulation of the base of the cochlea through bone conduction. Normal human hearing is recognised as having an upper bound of 15–28 kHz, [1] depending on the person.
Sonication can be used for the production of nanoparticles, such as nanoemulsions, [5] nanocrystals, liposomes and wax emulsions, as well as for wastewater purification, degassing, extraction of seaweed polysaccharides [1] and plant oil, extraction of anthocyanins and antioxidants, [6] production of biofuels, crude oil desulphurization, cell disruption, polymer and epoxy processing, adhesive ...
Approximate frequency ranges corresponding to ultrasound, with rough guide of some applications. Ultrasound is sound waves with frequencies higher than 20,000 Hz. Ultrasound is not different from audible sound in its physical properties, but cannot be heard by humans. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.
Standard ultrasound medical devices may also be used in some applications. Measurement of the acoustics used in sonoporation is listed in terms of mechanical index, which quantifies the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a non-thermal action based on pressure. [3]
As opposed to sonic vocalizations, ultrasonic vocalizations cannot be detected by the human ear. USVs serve as social signals, [2] and are categorized according to their frequency. Different categories of USVs are elicited in response to different situations and varying affective states. [3]