A conference in a hangar??
That sounds like having a phone call in a dustbin.
All the hangars I've ever been in have been cold, draughty and full of echoes. I would have thought that almost anywhere else would have been preferable to a hangar for holding a meeting.
If they are going to he hosting conferences, then a custom-built conferance centre with all the bells & whistles including soundproofing is the way to go.