Acoustic-Structure Interaction

Hi, I'm trying to solve a time-dependent Acoustic-Structure problem that consist in a acoustic pressure applied in the inlet of a tube as a boundary condition, in the outlet of this tube I applied a impedance condition with the value of c_air*rho_air, the sound pressure wave is suppose to hit the structure and transmit through it to the enclosure air cavity. Here I'm trying to simulate the response of the human eardrum to a high-intensity impulsive noise when protected by a earmuff. The problem is that the shell doesn't transmit the pulse, resulting in a pressure arround 0 Pa in the eardrum area. I'd done this before, in the time dependent Acoustic only module with sucess, but here in the Acoustic-Solid i'm stuck.

I'm using
Acoustic-Solid Interaction, Transient (asdt)->Time Dependant.
The Pulse is added to the software by an Interpolation Function, as shown in Img.1 attached.
I applied the boundary conditions as shown in Img.2 attached.

I'm sorry for my bad english and apreciate any help.