Sound and Soda Bottles with the TI-CBL

You can use the TI-82 together with the TI-CBL and the microphone probe, or sensor, to study sound and sound waves. As an example, we look at the sound produced when you blow across the mouth of an open, empty soda bottle.

The first step is to load the TI-82 program SOUND below into your TI-82. There are three ways to do this.

If you have the TI-82 Graph Link program and the Graph Link cable then you can download the program from your computer to the TI-82 in the usual way.
If the program is on another TI-82 then you can transfer it to your TI-82 using the linking cable.
As a last resort you can type the program in.

There have been numerous problems downloading programs for TI graphing calculators using the method above. If that method works, it is very clean. Sometimes, however, it doesn't work. In that case we can fall back on an older method, uuencoding, that is less user-friendly but more reliable.Click here for more information about this method. Then click here for a uuencoded (text file).

The TI-CBL, the program sound, and your TI-82 working together will record and graph 95 air pressure readings (the microphone measures air pressure) taken at intervals of 0.0001 seconds over a total period of roughly 0.0095 seconds. Then the program will draw a graph showing the recorded measurements. The measurements are saved in the list L₃.

Connect the CBL to the TI-82 by plugging one end of the linking cable into the linking port on each machine. Connect the microphone to the CH1 port at the top of the CBL. See the picture below.

Turn both the TI-CBL and the TI-82 on. The most common difficulty is that one of the units is off, either because it was not turned on or because it has automatically powered down after an idle period. Another common difficulty is that the linking cable is not completely plugged into both linking ports.

Now run the program SOUND in the usual way. You should see the screen below.

Blow across the mouth of an empty soda bottle to produce a low pitched hum. While you are blowing, press the ENTER key on your calculator. The CBL will record the data, then the TI-82 will read the data from the CBL and graph it. The screen below shows one experiment. Of course, your graph will be different because it will show your experiment.

Continue by experimenting on your own. Try various different soda bottles. Try using partially filled soda bottles. What differences do you hear? What differences do you see in the graphs? Click here for some ideas.