ADA Employment
Where good hearing is a critical qualification for the job, ADA does permit employers to discriminate. For example, a fire department was permitted not to hire a fireman with a hearing loss. The court reasoned that in the noise of a fire, where the safety of everyone depends on appropriate and coordinated action, a firefighter who couldn't hear instructions would be ineffective and a danger to others. Because water can render a hearing aid ineffective, the department was allowed to refer to the applicant's uncorrected hearing in making the decision.
Moreover, the ADA does not require an accommodation that would impose an "undue hardship" on the employer. That doesn't mean that the employer may weigh the cost of the accommodation against the financial benefit from providing it. Rather, the "undue hardship" test looks at whether the cost of the accommodation is one that the business as a whole can absorb.