This is a simple simulation of how changing the ear-canal pressure alters the admittance in tympanometry. In this simulation, you can specify the middle ear pressure and adjust the canal pressure to see how the admittance changes.
The red line represents the probe-tone frequency used for the tymp. You can select this by using the drop down box to select the frequency relative to the resonant frequency. How does the tymp change for values < 1 vs those >1?