While driving down from Nederland (elevation 7,500 ft) to Boulder (elevation 5,430) you consistently find your ears "popping". Out of curiosity, on one trip down, you note that your ears pop twelve times. Assume the ambient temperature is 65 degree F and that local pressure in Boulder is 25 inHg. Determine the pressure difference (in psi) required to make your ears pop. About how far under water would you have to submerge your ears to create the same sensation?