Hi Peter, 

Thank you for the recommendation, I used the three orthogonal planes to split and share all the geometry, both acoustic and mechanical components, but the meshing still failed. 

I believe the problem may be the very small air gap areas surrounding one of the mechanical components, this is reflected by the picture in green. I have tried contact size meshing for these small areas in contact and I've also tried some inflation for the areas of concern but neither worked. 

I've attached some pictures to described my issues. Please let me know if you see any problems or if I should try another method to generate the mesh. 

Thank you,