Dr. Greene, my son recently saw an ENT specialist because of mouth breathing, snoring and enlarged adenoids. While checking my son's ears, he commented on fluid in his left ear, which he estimated might have been there for some time. I have brought him for ear checks following ear infections. Why would my pediatrician not have mentioned it, and could my son's hearing be affected? He had a hearing test 3 months ago which was normal. Should he be tested again, immediately?

Fluid in the middle ear, which often goes undetected for weeks or months at a time, is an important hidden problem. This silent occupant of our children's ears can have lingering effects years after the fluid has cleared up.

The first golden moment you gazed at your son in the delivery room, he was already beginning an amazing journey of learning. And how do children learn? They take in the world by using their five senses. The sight of your face, the feel of your touch, the taste of your milk, the scent of your unique aroma, and the sound of your voice combine together to teach your son about the world.

Some children enter the world in silence.

Each year about 20,000 children in the United States are born with permanent hearing loss. Often this isn't discovered until the children are 3 years old and their language is noticeably delayed. We now know that hearing loss significantly impairs the ability to learn -- not just learning to speak but also to walk, to read, to write, to do well in school and to get along well with others.

The sooner hearing loss is detected and addressed, the better children will do overall. For this reason, I strongly support universal screening of hearing in newborns. Now that quality hearing tests for babies are inexpensive (as little as $25), failing to provide or at least offer this to all parents is irresponsible.

But these 20,000 children with congenital hearing loss are only the tip of the iceberg. In April 1998, the Journal of the American Medical Association reported a staggering 7 million children in the United States with hearing loss significant enough to impair the ability to learn. Most of these children have temporary hearing loss, but even though the hearing loss is temporary, the impact can last a lifetime.

Language development during the first few years of life is nothing short of amazing! A child is born unable to understand any words, yet is speaking in complete sentences within a few years. During this flowering of development, there are certain critical windows when different sounds are learned. For instance, someone who reaches 8 to 10 months of age without hearing Chinese will lose the ability to distinguish between some of the vocal sounds of that language.

What a tragedy if the language you miss out on hearing is your own! The most common age for temporary hearing loss is during that same precious time when the miracle of language development is unfolding. The most common cause for temporary hearing loss is the fluid in the middle ear space associated with ear infections. (Incidentally, you will find a chapter on what you can do to help prevent these situations in my book, The Parent's Complete Guide to Ear Infections.)

In a healthy ear, air fills the middle ear space. Sound waves enter the ear canal and vibrate the eardrum at the end of the canal, allowing us to hear. Whenever a child has an ear infection, germ-containing fluid enters the middle ear space from the back of the nose or throat.