How Can We Sense So Many Different Sounds from a Distance? [v2.1]
In this unit, students start by observing a perplexing phenomenon. When a sewing needle taped to a cone is dragged over the surface of a plastic disc that is spun underneath it, it produces voices and musical notes. This leads students to start wondering about other sound-related phenomena, which in turn leads to wealth of new questions about 1) What causes different sounds? 2) What is traveling from a sound source to our ears? 3) How do we hear and why do we hear things differently in different places? and 4) How do electronic devices (digital sound sources) produce and detect sounds?
By investigating concepts like loudness and pitch, students learn how to model vibrations to convey important ideas about changes in the frequency and amplitude of vibrations that can explain different characteristics of sounds. What they figure out from this helps to answer their initial questions about what causes different sounds.
By testing various types of materials and using varying simulations, students figure out how sound travels from one location to another through matter. What they figure out from this helps answer their initial questions about what travels from a sound source to our ears.
By investigating the internal structure of the ear and testing how different structures can redirect sounds, students figure out how sounds can be detected, reflected, absorbed, and transmitted. What they figure out from this helps answer their initial questions about how we hear and why we hear things differently in different places.
By dissecting an electronic speaker, building and testing a speaker of their own design, and analyzing how Edison wax cylinders and vinyl records were produced, students figure out how analog and digital audio information can be encoded and played back. What they figure out from this helps answer their initial questions about how electronic devices (digital sound sources) produce and detect sounds.