Lesson 8

Instrument Signature

Card Sorting Examples

Example 1

Example 3

Example 2

Goal: Students should be able to justify their categories, whether based on size, shape, material, the way it's played, or the way sound resonates.

Tips: Have students add more instruments to the list. The more unusual, the better!

See the list by Wikipedia below for references to musical families.

Instrument Signatures

Sound Spectrum

Use the websites below to show how harmonics can be added to change the sound you hear.

You can also download the PhyPhox app on your cell phone for some really cool demonstrations and live data collection.

PhET Simulation:

Play with the Discrete Lab making sure to hit the music button to hear the sound produced. Try the different waveforms and change the graphs. Show the equation only if students are interested. Change the amplitudes in one direction.

Then play the Wave Game, getting student input to match the wave.

Lab - Speed of Sound

Materials

General Set of Tuning Forks (one per class to distribute one fork per group)
Graduated Cylinder filled with water (one per group)
Open Tube (aka Golf Tube) (one per group)
Meterstick (one per group)

Instructions

Place Students in Groups of 3-4
Before passing out materials, demonstrate for the class. This can be easiest to do on the floor, having a student volunteer helping you as you move the tub up and down. You can do it completely on your own if you wish, as seen in the video below. Emphasize that they will have to listen very carefully to hear the resonance of the harmonic.
After demonstrating, pass out materials and monitor student behavior.

PXL_20230523_160711213.TS~2.mp4

Important tips

Students need a quiet work environment for this to work well. If possible, allow students to spread out as much as possible while still being able to monitor all groups.

Measure from the water line to the top of the tube.

Make sure the meterstick lines up with the water line to get the length of the resonating frequency. The water line acts as a closed surface that the sound wave reflects off of.

Orientation of the tuning fork matters

Remind students of the lesson where they could hear the tuning fork best. If students have forgotten, they can slowly turn the tuning fork near one ear to hear the loudest orientation.

Data Ranges for the First and Third Harmonics

Speed of Sound Academy

It is most likely that students will be discovering the THIRD harmonic.

Check the table on the left for acceptable data ranges given a speed of sound range between 330-355 m/s.

Tuning forks less than 304 Hz will be challenging with our materials. It is suggested to use only tuning forks greater than 304 Hz.

Extra time? Mark Rober's video below shows the World's Largest Horn and measure the speed of sound. If you only want to see the speed of sound section, it starts at 340 seconds (5 minutes, 40 seconds) and goes to about 7 mins 28 seconds).

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