I'm guessing - as long as your "disability" doesn't interfere with your ability to do the job, and as long as you can still do the job with some sort of assistance (such as a hearing aid or BAHA?), then I'm not sure they can discriminate against you.
I'm NOT SSD, however, I am hearing impaired on my AN side, and it DOES present significant challenges in my job. I work in prison, and often have to walk down long corridors with cells on each side, and talk to the inmates through the cell doors. Depending on which side of the corridor I'm on, then it can present a challenge with making sure my "good" ear is nearest the person speaking. My hearing aid is marginally helpful with this problem.
The flight attendant job would be similar, in that your AN ear would sometimes be closest to the travelers. I know that, for me, this would be a VERY frustrating job. Seems like a situation in which BAHA might be real useful. Maybe some of our BAHA folks will chime in here.