Can my employer purchase my hearing aids and use it as a business expense? They are required to perform my job.

[WillK]

Technically yes. Your employer would need to include the amount they paid for your hearing aids on your W-2 as income (per the IRS rules), and then they can take the expense on their business return. 

[captlyon]

Does the Corporation or the employee have to pay Social Security and Medicare on this benefit?

[MarilynG1]

If your employer included the amount of the benefit on your W-2 wages, then yes, Social Security and Medicare would be paid on this amount.

A fringe benefit is a form of pay for the performance of services, given by the employer to the employee. For example, Personal Use of a Company Car (PUCC), in which you allow the employee to use a business vehicle for personal use, is a type of fringe benefit.

Non-cash fringe benefits should ideally be reported on a paycheck where the employee has regular wages to offset the taxes on the fringe benefit items.

Click this link for more info on Employee Fringe Benefits.