Editing Ultrasound (section)

===Ultrasonic humidifier===
The ultrasonic humidifier, one type of [[nebulizer]] (a device that creates a very fine spray), is a popular type of humidifier. It works by vibrating a metal plate at ultrasonic frequencies to nebulize (sometimes incorrectly called "atomize") the water. Because the water is not heated for evaporation, it produces a cool mist. The ultrasonic pressure waves nebulize not only the water but also materials in the water including calcium, other minerals, viruses, fungi, bacteria,<ref>{{cite journal | vauthors = Oie S, Masumoto N, Hironaga K, Koshiro A, Kamiya A | title = Microbial contamination of ambient air by ultrasonic humidifier and preventive measures | journal = Microbios | volume = 72 | issue = 292–293 | pages = 161–6 | year = 1992 | pmid = 1488018 }}</ref> and other impurities. Illness caused by impurities that reside in a humidifier's reservoir fall under the heading of "Humidifier Fever".

Ultrasonic humidifiers are frequently used in [[aeroponics]], where they are generally referred to as [[fogger]]s.