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Investigating Sound – Investigation 2 CAP


Investigating Sound: Investigation 2 – CAP


In this CAP we would like for you to solve a problem by constructing a tool. In the lab, you performed experiments with sound. In this CAP you will build and test a megaphone as a means of increasing the volume of your voice.


This slide is included to remind you of your recent lab experience in which you learned that sound waves travel through solids, liquids, and gases. In this CAP we will be concentrating on the sound that travels through the air and reaches our ears.


This slide proposes a question, “Can we build a simple device that can make a sound easier to hear?” In this case, we are talking about making a sound louder, which is increasing its volume.


This slide shows the woman on the left cupping her hands to her mouth while the woman on the right puts her hand to her ear to hear better. In the next slide, the concept of a megaphone will be introduced. However, at this point, you might ask yourself, “Can you think of any tool or device that the woman on the left could use to make her voice louder?” 


Interestingly, this slide depicts how a useful device may simply be an extension of a human structure. In this case, the megaphone essentially extends the size/area of the woman’s cupped hands. Can you think of other examples in which a device is used as an extension of the human anatomy? Potential answers include: a baseball glove to extend the size of a hand, a step-stool to make you taller, shoes to toughen the soles of our feet, a hat to help our hair protect us from too much sun, a club to extend and harden the arm for defense, and so on. Many inventions were conceived as simple extensions of the human body.


This slide and the next simply show examples of how megaphones are used (or have been used) and who uses them. Here we see a cheerleader and a film director using a megaphone.


This slide shows additional examples of how megaphones are used. Here a lifeguard and a bugler use a megaphone. Electronic devices such as microphones have largely replaced megaphones in most instances.


This slide presents the materials that you can use to build your own megaphone.


This final slide shows the megaphone in use. Be sure to experiment with your megaphones. The slide suggests two things to try: the speaker inverting the megaphone (which should decrease the speaker’s natural volume) and the listener using a megaphone (which should increase the volume to them). As noted, do these experiments outside if possible. This is to cut down on the reflected sound that occurs indoors from ceilings, floors, and walls.