Ultrasound Scanner是声波with频率higher than the upper audible limit of humanhearing.Ultrasound Scanner是no different from ‘normal’ (audible) sound in its physical properties, except in that humans cannot hear it. This limit varies from person to person and is approximately 20千赫(20,000 hertz) in healthy young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances.超声成像或超声检查经常使用medicine. In thenondestructive testing产品和结构，Ultrasound Scanner用于检测隐形缺陷。从工业上讲，超声用于清洁，混合和加速化学过程。动物，例如bats和海豚use ultrasound for locating猎物和障碍。^[1]Scientist are also studying ultrasound usinggraphene膜片作为一种交流方法。

Humans

The upper frequency limit in humans (approximately 20 kHz) is due to limitations of the中耳.Auditory sensation如果高强度超声直接馈送到人类头骨并到达cochleathroughbone conduction，不穿过中耳。^[4]

Children can hear some high-pitched sounds that older adults cannot hear, because in humans the upper limit pitch of hearing tends to decrease with age.^[5]一个美国人手机公司用它来创建据称只能由年轻人听到的戒指信号。^[6]但是许多老年人可以听到这些信号，这可能是因为上听力阈值与年龄有关的恶化存在很大变化。蚊子是使用高倾斜频率阻止的电子设备游荡by young people.