If you have a Texas Instrument CBL (Calculator-Based Laboratory) with either a TI-82, TI-82, TI-85/CBL or TI-92 Graphics Calculator and a microphone for use with the CBL at your workstation then you can look at some sound waves.
You will need the program SOUND on your graphics calculator. Check to see that it is there. If so, click here to skip ahead. If it isn't then you can either type it in or if your workstation has a TI-Graph Link cable and the appropriate software installed then you can download the program from this computer to the calculator. The TI-82, TI-83, TI-85/CBL and TI-92 programs are listed below. Next to each one is an icon. Clicking on the icon launches the TI-Graph Link software with the appropriate calculator program.
The TI-CBL, program SOUND and your graphing calculator together will record and graph air pressure readings (the microphone measures air pressure) taken at intervals of 0.0001 seconds. If you are using the TI-92 it will graph 239 readings for a total of roughly 0.0239 seconds. If you are using the TI-82 or TI-83 then it will graph 95 readings for a total of 0.0095 seconds. If you are using the TI-85 then it will graph 127 readings for a total of 0.0127 seconds.
Connect the CBL to the calculator by plugging the linking cable into the linking ports at at the bottom of each machine. Connect the microphone to CH1 port at the top of the CBL. See the picture below.
Turn both the TI-CBL and the graphing calculator 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 on either the TI-82, TI-83, TI-85/CBL, or TI-92. To run the program on the TI-92 type sound() and then ENTER from the HOME screen. On the TI-85 you should see the screen below. The TI-82, TI-83, and TI-92 displays are similar.
Hum a low pitched tone. While you are humming, press the ENTER key on your calculator. The CBL will record the data, then the calculator will read the data from the CBL and graph it. The screen below is from the TI-85. Of course, your graph will be different because it will show your hum.
You can remove the words at the bottom of the screen by pressing the CLEAR key. See the picture below.
Continue by experimenting on your own. Look at high-pitched hums and low-pitched hums. What happens if two people hum at the same time?
