According to the Mishna (83b), payment for shevet – loss of wages during the time that the person recovers – is established by paying him the amount that he could have made as the watchman over a cucumber patch. The Gemara brings a baraita that explains that this is a fair wage, since the person who caused the injury has already paid nezek and has therefore already worked out what he owed him for the loss of his normal salary.
Rava continues explaining that this is true for a person who lost his arm. If he lost a leg, the nezek would cover the value of the leg and the shevet would be evaluated based on his being someone who sits and guards an entrance. If he was blinded, he would receive the value of his eye as nezek and would be paid shevet on working a hand mill. If he was made deaf, he is seen as unable to work and the nezek would take that into account.
The Ra’avad explains that even though a person with a permanent injury may be able to perform work that is more specialized – and more valuable – than the jobs described by Rava, nevertheless, once the injured person has been paid nezek on his permanent loss, the shevet that he receives is based on the normal job that someone with his disability can perform. According to Tosafot, Rava’s statement is true for a simple laborer, but if a person will be able to perform more specialized work even after his injury, then the nezek would have taken that into account and the shevet that he will receive would reflect the salary that he would be making at that time.
In explaining the ruling that a heresh – someone who was deafened – has no value as a worker, the Ra’avad explains that no one will hire him since they cannot communicate with him to tell him what they need done.