Sorry I didn’t write about my sound demos last week. The end of the school year is just too busy. Here’s the basic list:

I used the function generator to show interference, both constructive and destructive by setting each speaker to a slightly different frequency. You can create some really good beats. When you feed the signal in to Visual Analyzer (VA) you can see the beats as well.

I illustrated destructive interference by setting both speakers to the same frequency and pointing them at my microphone. I slowly changed the distance to the microphone of one of them until the o-scope showed nearly complete destructive interference. If you were ambitious you could use this to determine the wavelength of the sound as well.

Using VA’s function generator I generated a frequency tuned to a graduated cylinder to cause it to resonate. I used a cheap $0.50 speaker that was to quite to hear until it was brought near the graduate. You could use this to determine the speed of sound if you were so inclined.

I used a variety of musical instruments to show the different numbers and strengths of relative harmonics using the FFT in VA to illustrate why different instruments sound different even when playing the same note.

Sorry I haven’t posted in a couple of weeks. I’ve been a bit busy and haven’t really stumbled across anything new and cool in educational technology.

For the next week or so I’ll be teaching sound in my freshman physical science course. I use an oscilloscope program on my computer to do this. I’ve seen several different programs for doing this and most of them cost a lot of money. The one I use is free and from the descriptions I’ve read of the costly ones it is better.

I use Visual Analyzer. The download site is in Italian but all you need to do is click on Download VA near the upper left. For those interested I’ve also created some simple instructions on how to Use VA. Over the course of this week I’ll post how I’m using VA to teach sound.