ultrasound

[uhl-truh-sound]

noun

1. Physics.,  sound with a frequency greater than 20,000 Hz, approximately the upper limit of human hearing.

2. Medicine/Medical.,  the application of ultrasonic waves to therapy or diagnostics, as in deep-heat treatment of a joint or imaging of internal structures.

ultrasound

/ ˈʌltrəˌsaʊnd /

noun

1. ultrasonic waves at frequencies above the audible range (above about 20 kHz), used in cleaning metallic parts, echo sounding, medical diagnosis and therapy, etc

ultrasound

1. Sound whose frequency is above the upper limit of the range of human hearing (approximately 20 kilohertz).

2. See ultrasonography

3. An image produced by ultrasonography.

ultrasound

1. A method of diagnosing illness and viewing internal body structures in which sound waves of high frequency are bounced off internal organs and tissues from outside the body. The technique measures different amounts of resistance the body parts offer to the sound waves, and then uses the data to produce a “picture” of the structures. Ultrasound is often used to obtain an image of the developing fetus in pregnant women; the image can confirm the presence of twins or triplets and can be used to diagnose some abnormalities.

When an image of the inside of the body is needed, ultrasound is often considered a safer alternative to x-rays. Like x-rays, ultrasound involves exposure of the body to a form of radiation; unlike x-rays, ultrasound has not been shown to be carcinogenic.

Word History and Origins

Origin of ultrasound¹

First recorded in 1920–25; ultra- + sound ¹

A Closer Look

Many people use simple ultrasound generators. Dog whistles, for example, produce tones that dogs can hear but that are too high to be heard by humans. Sound whose frequency is higher than the upper end of the normal range of human hearing (higher than about 20,000 hertz) is called ultrasound. (Sound at frequencies too low to be audible—about 20 hertz or lower—is called infrasound.) Medical ultrasound images, such as those of a fetus in the womb, are made by directing ultrasonic waves into the body, where they bounce off internal organs and other objects and are reflected back to a detector. Ultrasound imaging, also known as ultrasonography, is particularly useful in conditions such as pregnancy, when x-rays can be harmful. Because ultrasonic waves have very short wavelengths, they interact with very small objects and thus provide images with high resolution. For this reason ultrasound is also used in some microscopes. Ultrasound can also be used to focus large amounts of energy into very small spaces by aiming multiple ultrasonic beams in such a way that the waves are in phase at one precise location, making it possible, for example, to break up kidney stones without surgical incision and without disturbing surrounding tissue. Ultrasound's industrial uses include measuring thicknesses of materials, testing for structural defects, welding, and aquatic sonar.

Example Sentences

For my 40th birthday, I’d decided to treat myself to a special trip—joining the women worldwide who fly to South Korea for beauty treatments involving salmon DNA, ultrasound tighteners and lots of lasers.

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A doctor used a thin needle attached to an ultrasound probe to puncture the follicles and remove fluid that contains an egg within it.

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After her second ultrasound, a doctor assumed she knew she only had one kidney, which she did not.

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Over the years, researchers experimented with roost cameras, military radar, hot-air balloons with ultrasound recorders, and GPS trackers -- struggling to create tools light enough for the bats to carry.

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A few generations ago, the ultrasound would show a grainy blob.

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