Journal 4/26/16 Why do you think God gave us the sense of hearing? Give 3 concrete examples. Objective Tonight’s Homework To learn some technologies and uses for sound waves p 457:9, 10 WDYL: 2

Notes on Sonar and Ultrasound One of the most interesting uses we have for sound technology is in sonar and ultrasound. Both of these use the same technique – to bounce sound waves off an unseen object to create a picture of what’s being seen where. In sonar, this is done by sending sound waves into water and seeing if it bounces off anything. This was used in WW II to detect submarines, mines, and other underwater threats. Nowadays, it’s used to detect shipwrecks and keep oil rigs over the correct spot.

Notes on Sonar and Ultrasound Ultrasound is where very high frequency sounds are sent into an object and reflected to create a picture of what’s inside. The most common application for this is generating ultrasound images in pregnancies. Most of you have probably seen ultrasound images of unborn babies. Ultrasound is also used in cleaning, as the high- frequency vibrations are great at shaking dirt and dust off things like jewelry (or even teeth!). From this, we want to note that sound waves can be used for a lot more than just listening!

Mythbusters on Resonance Let’s watch the Mythbusters break some glass with sound!

Decibel Device Thursday, you’re going to be bringing in your decibel- measuring device and testing it out to see how well it works. This means you have the rest of class to work on it!

Exit Question Bats use echolocation, which is similar to sonar and ultrasound. How do you think it works? Bats shake their enemies apart with sound waves Bats talk to their prey to scare them with high sounds Bats listen for sound waves bouncing off creatures Bats hear the noises made by prey and can track them that way Bats don’t use echolocation. Mr. C. is being tricky None of the above