While the SS system is still around, it's not quite as stable as we would like. So, there should be more rules. Like say someone found a job while on SSDI, he/she should be pushed to go for full time if possible. I have a co-worker who can work more but she doesn't want to. She is currently working about 20-23 hours a week. Whenever she gets a quarterly bonus or a holiday bonus, she cuts back her hours temporarily so she stays under the income limit. When she gets her annual raise, she also cuts back her hours a bit. Her husband makes a nice salary because he worked for some electrical wiring company for about 30 years (retiring in a few years) and he does a lot of overtime. She does have a long history of employment as well; she was laid off from her acocunting job before coming to work at Walmart. She wouldn't let go of her SSDI until she feels her debt (mortgage, loans, etc) have been mostly cleared. In other wods, she is counting on SSDI as a secondary source of income and relishes the free time she can get. She knows that her retirement checks will be smaller, but she's not worried because her husband will be bringing in fat SS checks when he retires, on top of his pension payments.
So, a general rule would be checking with the emlployer to see if more hours could be given to the SSDI recipient. If more hours are possible, SSDI checks are automatically pared back so the recipient is working more. If the recipient truly can't work more, the medical documents will back that up. Hearing loss alone wouldn't prevent a person from working more.
One out of one thousand people is deaf. Plus, blind people, people in wheelchairs, children who lost a parent, widows, Down Syndrome, mental health issues, children with disabilities, and so on. We are now supporting one person with tax money paid out by three workers. Let's be realistic. SS needs reform and stricter rules. We should be more flexible about Medicare and let all people with disabilities have Medicare no matter if they are working or on SSDI. There should be federal programs providing jobs directly to people with disabilities if they are experiencing discrimination.