Use a microphone to observe the nodes and antinodes in a long pipe. The pipe can be open, closed at one end, or closed at both ends. Measure the resonant frequencies, and use your data to calculate the speed of sound in air and in other gases such as helium.
Optional: verify the pressure independance and the temperature dependance of the velocity of sound in an ideal gas.
You will also learn how to use the HP 5315B Universal Frequency Counter, and about important safety procedures for using gas cylinders.