In the graph used to show the difference between linear and logarithmic (sometimes called "audio taper") pots, assuming the values of the X and Y axis are both linear - then the linear pot line should be straight, and the logarithmic pot line should be a simple bow curve bending towards the bottom right hand side.
If the graph is supposed to account for the Fletcher-Munson curve (now more commonly referred to as simply the "equal loudness curve" due to further study that has been carried out in that field since the original publication by Fletcher and Munson of their work) then those shaped curves may be accurate, but as I read this otherwise-informative piece, the representation of the two different curves is wrong and ought to be amended.
I found a wealth of further information regarding potentiometers at the following URL -
http://sound.westhost.com/pots.htm
