Higher wage for newly hired employee?

My hubby, a Maintenance Tech in this big company for 10 years recently found out the newly hired employee (Maint Tech) is earning $4 higher than he's per hour salary. My hubby had Two year degree in Mechanic, had boiler license and Maintenance Tech at the Army Reserve for 15 years. The newly hired guy dont have degree, dont have boiler license, not much experience in Maint Tech but was trained at the Air Force as aircraft mechanic for 6 years. Now my hubby is training this new guy, this newly hired employee dont even know how to operate and fix a simple machine and my hubby told that this new guy will going to get a raise in a few months. My husband brought this up to he's supervisor but then he was told to go directly to HR. He went to HR dept and talked to the HR Manager about this things but then the HR did not deny it, they are hiring new Maint Tech because they cant find anybody and that is the market price today. My husband didnt like it, and he said that he will leave the company as soon as he find a different job. Is the HR lady is right for hiring new people for a higher wage than old employees? My husband has been a good worker for this company and always get a recognition, but then they didnt want to give him a raise. I need an advice about this, my husband lost his motivation at work and wanted to find a different job, the situation really bothers him, training a new guy that is earning more than what he makes. What advice should I tell him to make him feel better? Is quiting and finding a new job is the solution to this? Any advice or idea is highly appreciated. Thanks.