  Relatively inexpensive and readily commercially available equipment (such as
digital recorders, MP3 portable speakers and tie-pin microphones), allowed a
team of students from McNeese State University to measure the speed of sound in
the atmosphere as a function of altitude. The experiment was carried as a
payload (in the context of a NASA funded student program called La-ACES) on a
high altitude balloon that reached a maximum altitude of 101,000 feet. Not
withstanding substantial environmental noise, our particular experimental
design allowed for the filtering of the signal out of the noise, thus achieving
remarkable accuracy and precision. The speed of sound measurement was then used
to set limits on the abundances of the main molecular components of the
atmosphere (diatomic nitrogen and oxygen). Bayesian analysis was used to set
meaningful values on the uncertainty of our limits. It is our experience that
students find intutive and appealing this type of probability method.
