Deaf Survivors and Witnesses to 9/11

Check this movie preview of an upcoming film by Jade Film. They produced a motion picture called 9/11 Fear in Silence: The Forgotten Underdogs. It's about the stories of deaf and hard of hearing survivors and witnesses of 9/11 who tell their stories through their eyes and hands. Was silence that almost killed them or was it neglect by other people who didn't know any better?