This is a very concerning symptom. I would strongly recommend that you have your son see his primary care doctor
. It is likely he will need to be referred to a specialist in the area of hearing -- this is an Ear-Nose-Throat doctor
. In addition, another healthcare professional known as an audiologist
will be needed in order to perform testing. This should be assessed. Hearing is obviously an important function and as loss may be permanent, it is imperative to investigate this early.
Hearing is a complex process. In general, the sound waves hit the tympanic membrane (ear drum) and through a series of bones activate the nerve. The nerve than carries the sensation to the brain. Therefore problems in the ear drum / bone can causes problems in hearing -- this is known as conductive hearing loss. The other category of hearing loss is problems with the nerves and brain -- this is known a sensorineural hearing loss. Determining which category of hearing loss is occurring is the key. In order to do this your primary care doctor can do some tests. Beyond that, formal testing with by an audiologist is needed.
Without more information it is hard to say. That being said, loud music -- or acoustic trauma -- is the most common cause of hearing loss. This is reversible -- so avoiding loud music and ear bud headphones may help.