If you are asking if this is "mental" as in a psychological problem, I do not have an opinion. But if you mean something physical that has affected his brain, then yes. There are a multitude of complex issues that can affect the way genes work, mitochondria work, brain works, etc, and it often can greatly affect brain neurons and function.
One common brain symptom is the inability to filter out sounds. They can feel overwhelming. Some kids are born this way and get better over time. Some kids have it develop and it can be a symptom of worse to come. It can happen from psychological factors... of course, and it can be physical by epigenetic changes triggered by toxins, drugs, severe stress, viral infections, etc. It can be hormonal problems, nutritional problems, allergies, brain lesions, migraines....
And yes, this can be a prodrome to a set of symptoms which collectively get labeled "schizophrenia". The problem is that there is currently no medical diagnostic test for that, and many different possible etiologies, so it is only diagnosed by the symptoms. However, there are risk factors, and methods to help lower risks and severity. Any way they look at that -- the earlier steps (fish oil, lifestyle changes, pharmaceutical meds, etc) are taken, the better the outcome, statistically.
We cannot diagnose what is happening with your son, so I would start with getting him to a doctor for a general check-up, and let the doctor know that your son has become very sensitive and irritable to sounds.
You can take a look at caffeine intake, sleep habits, nutrition, allergies, possible drug use, etc.
And I'll hope that it is just a phase he is going through, since that is also a possibility.
You might get some ideas from http://www.itsnotmental.com , and in the meantime, ask him if he would like to use ear plugs, or if music might help him. Hmmm... not sure if this would help or irritate him, but consider a device that produces "white noise" in his room.