PDF Lesson

### Lessons 1: Making Waves

An oscilloscope is an electrical device that can convert sound waves into a visual display. A sound wave moving through air is actually a longitudinal wave. An oscilloscope changes the sound wave into a transverse wave that appears on a screen. Can you use the visual display of an oscilloscope to find out some basics about sound waves?

### Doing the science

1. Start the Modular Synthesizer Simulation by clicking on the "Sim" tab.
2. Make sure that the sound is turned on and your volume is at an appropriate level on the device you’re viewing the simulation.
3. Click the "D" key once (the second white key at the far left of the keyboard).
4. Note and record in Table 1 the frequency of the sound that is displayed in the top middle portion of the screen. Listen carefully to the note being played.
5. Count and record in Table 1 the number of peaks (highest points on a wave) from the start of the wave to a time of 0.005 seconds. You might have to click the "D" key again if the sound wave disappears.
6. Repeat steps 3 – 5 for the "F" key (the fourth white key from the left) and for the "B" key (the second white key from the right). Make sure to record your data in Table 1.

Table 1.

 Key Frequency (Hz) Number of Peaks Relative Pitch “D” “F” “B”

### Do You Understand?

1. What is the difference between a longitudinal and a transverse wave?

2. Describe the relative pitch of the three keys you played ("D," "F," and "B")

3. Describe the relationship between the pitch of a sound and the sound’s frequency.