Imagine designing an experiment in which the presence of a gas is determined by simply listening to the gas with your ear. The human ear can detect pressures as low as 2 x 10^(-5) Nm^(-2).
Assuming that the eardrum has an area of roughly 1 mm^2, what is the minimum collisional rate that can be detected by ear? Assume that the gas of interest is N2 at 298 K.