Is it expensive for Airports to Provide More Services for the Deaf on Planes?

Is it expensive to provide services for the deaf in airports? They could give the deaf passengers an option to sign up for certain services before their flights. When they get their tickets, there could be a yes and no box with questions asking if they want closed captioning services on their flights and an interpreter and so on. I understand there is no point in providing closed captioning services on every single plane if there aren't any deaf passengers on some of them. So, maybe they could have the deaf people sign in and register for a special flight service that has closed captioning. Then they could be put on that certain plane that has the services provided. This goes for the gates as well. They should send the deaf people to the gates that already have closed captioning on the overhead screens there. If there is a deaf passenger on a certain flight and there are no closed captioning screens at the gate, then they should change the gate to one where there is a closed captioning monitor. That is only fair for the deaf passengers, they need to feel comfortable as well as everyone else. I know there aren't that many deaf people on a plane at given times from experience. I have boarded a plane at least twice a year in the past 40 years. And I have not seen any deaf people on any of my flights. But the airports could make arrangements to install a closed captioning monitor in every plane, in at least two seats for the deaf passengers. That way everyone is happy with the deaf passengers included.