In today's studio-lab you will investigate how to build waveforms. You have two primary goals:
-
Understand how a specific waveform is constructed by adding together simpler waves that are harmonically related.
-
Understand how the phase of the components can affect the shape of the waveform
Making Waves
Download and install the PHeT Java applet Making Waves. Spend the next 20 minutes "playing" with the applet. Be sure to explore the various menu options - you can't break anything!
KEY POINT: Any waveform that has "sharp" bends of kinks must have high frequency components (higher harmonics). How does this affect the tonal quality?
When you are ready please complete 1 each of levels 8, 9 and 10
Phase
Download the spreadsheet wavesup.xls.
Create a simple wave form made by adding the 1st and 2nd harmonics (leave all other amplitudes 0). Let A1 = 1 and A2 = 0.5. Sketch the waveform. Now adjust the phases of the two waves and note what happens to the wave shape.
Next, try to reconstruct the following waveforms:
- square wave
- sawtooth wave
Once you have made these waves begin to adjust the phase sliders on the components and note how the shapes respond.