I think the question is Does a dragon have Sonar hearing like a bat. I would say not otherwise it would be probably be blind.It doesn't have to.
It will reflect sounds made by the dragon, the party, and anything else near it that DOES make any noise, thus it's perfectly detectable using hearing.
I doubt that the wall of force would give off that much of an echo as it is relativly small and only one plane. Its not like being in a tunnel where the sound has no where else to go.