How do ultrasounds see babies?

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Answer

Ultrasound works the same way as a ships sonor or a bats echolocation. Now, didn't that help?

When sound travels through a media like air or water it travels at a certain speed and some of the energy is absorbed by the media and some bounces off whatever it hits. This is like any other echo you have experienced in air. You shout and a certain time later your words come back to you.

By knowing the exact frequency of the orignal sound and density of the media the sound is moving through and some advanced math, you can calculate the exact distance the object the sound bounced off is from the source of the sound. With me so far?

When the health professional does an ultrasound they pass a little speaker and microphone (its one piece) over the womb. The speaker puts out a very high frequency sound of a known frequency. The sound that hits the baby bounces off and comes back to the microphone. With the help of a very fast computer the distance is calculated and each distance is assigned a gray scale value from white to black. Since this is done with such precision and accuracy, the tip of the nose would have one shade of gray while the cheek that is just a little bit farther away would be a little darker. By assembling all these gray shades side by side you start to see the image.

Have you ever taken a pencil and rubbed it over a piece of paper to see what someone has written on the previous sheet? Well this is kinda how the image looks.

By making adjustments to the intensity of sound and controlling the some other factors, the health professional can actually look inside the baby to see the heart or other organs. Ultrasounds are painless to the patient and painless to the baby. They even do ultrasounds on adults to see kindney stones or how the heart is operating. I've had an ultrasound on my heart. It was strange to watch the valves of my own heart operate! It didn't hurt.

First answer by FaqFarmGeo. Last edit by FaqFarmGeo. Contributor trust: 210 [recommend contributor]. Question popularity: 62 [recommend question]