Have you ever seen a picture of a baby inside his or her mother’s body? If so, you may have wondered how doctors get their cameras inside the body to take these pictures.
Would you believe those pictures don’t come from cameras? They’re actually made with sound!
Ultrasound — also called “ultrasonography” — is a medical technology that uses high-frequency sound waves and their echoes to create images of what the inside of the body looks like. The scientific principles that make this possible are similar to those that allow bats, whales and dolphins to “see” what’s around them using echolocation.
Ultrasound technology was actually first developed during World War I to help track submarines underwater. The technology was called “SONAR,” which stands for SOund Navigation And Ranging.
Ultrasound wasn’t used for medical purposes until the 1950s. The high-frequency sound waves used in ultrasound technology cannot be heard by human ears.
Instead, a special tool called a “transducer” is used to send sound waves and detect the echoes that return. As the sound waves pass through the inside of the body, different types of tissues conduct sound differently.
A variety of echoes is produced. These echoes can identify the size and shape of organs and other objects inside the body.
A special computer in the ultrasound machine can read these echoes to produce a picture of what the inside of the body looks like. Usually, doctors use an ultrasound to study a particular part of the inside of the body, such as an internal organ… or a pregnant woman’s unborn baby!
Ultrasound technology is very safe, and doctors like it because it is noninvasive. That means it does not involve penetrating the skin or body.
Ultrasounds are used often during pregnancy to help doctors keep an eye on a baby’s development. There are also many other medical uses for ultrasound technology. Ultrasounds have been used to explore most parts of the body to diagnose various issues with internal organs.
Recent advances in technology have resulted in the development of 3D ultrasound imaging. By using multiple two-dimensional images, special computers are able to combine multiple images into a 3D image.
Doctors believe this new technology will lead to earlier detection of cancer, as well as the ability to better assess blood flow in organs and development of babies in their mothers’ womb.
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How is milk produced?
Your question is a great idea for a future Wonder of the Day®, Catherine! Thank you for visiting Wonderopolis today and suggesting it!
We loved the video!! We saw how you can see the sound. We knew a bus was coming when we heard its sound. We talked about seeing the sounds in ultrasounds, too.
Happy Monday, Kerrick Elementary School! Thank you so much for sharing your comment with us today! We’re glad you learned a lot of new things about sound and ultrasounds! Did you happen to visit yesterday’s Wonder #413 yet? We think you will really appreciate where we got the INSPIRATION for it!
Dear Wonderopolis,
We love that the word ultrasound gives us a clue for how ultrasounds are made using sounds not a camera! This WONDER made us WONDER if humans can’t hear the sound waves, can dogs hear these sound waves?
Happy Wondering, TEAM Caisse’s 5th grade Reading Class
That’s a GREAT question about dogs being able to hear sound waves, TEAM Caisse! We will have to do some more WONDERing about that, ourselves! Thank you for letting us know you liked today’s Wonder and that you learned some new things by exploring it together!
More interesting information.
Thanks again. 3D ultrasound imaging, that’s awesome! 
-elango
We’re glad you learned some interesting new things about ultrasounds today, Elango! Thank you so much for visiting Wonderopolis!
Dose it show the sound?
Hi, Gianna! A special computer inside the ultrasound machine reads echoes of sound waves as they bounce off different parts of the body. Then, the computer translates the echos into a picture of what the inside of the body looks like! Pretty cool, huh? Thanks so much for hanging out in Wonderopolis today!
Hey, Wonderopolis. How does hair grow and were does it grow from?
That’s a GREAT question Abdilahi! It would make a really interesting future Wonder of the Day®! Did you know there is already a Wonder about hair? It’s past Wonder #6 – Why Does Hair Turn Gray? Here’s a link straight to it so you can learn a little more about hair: http://wonderopolis.org/wonder/the-hair-raising-truth-about-going-gray-2/. Thanks for leaving us this comment today!
If you can see sound, how do you see it? Is hearing sound like sound waves? Exactly what does sound look like? I would really like to know, because me and my friends did an experiment where we looked closely to the radio to see if we got to see anything, and we didn’t!
Please write back. I would love to know the answer.
Those are all great questions, Amber! High-frequency sound waves (the kind of used in ultrasound technology) cannot be heard by human ears. Those sound waves do, however, create “echoes” when they bounce off objects. Ultrasound machines interpret those echoes into an image that we can see! So, we’re not really “seeing” the actual sound, but instead an image that the ultrasound machine creates from the sound wave echoes!
This is cool, and I loved the video.
We have really enjoyed hearing from our Wonder Friends today about how much they enjoyed the video for this Wonder! Thanks for being one of those AWESOME Wonder Friends, Luis!
What!? How can you see sound?? That is some pretty cool stuff! If that’s legit, man, that’s pretty sweet.
Thank you for leaving us this enthusiastic comment today, Mac! Ultrasound machines are pretty sweet, we agree! They help make a picture of the sound wave “echoes” that bounce off objects so we can “see” what the inside of things (like the human body) look like!
I don’t get how you can see sound.
Hi, Sammi! Sound waves create “echoes” when they bounce off objects. Special machines, called “ultrasound machines,” translate those echoes into an image that we can see on a computer screen or a printout! That’s how we “see” sound!