The brain and its nervous system are astounding in their complexity and capability. The nervous system does not start with the knowledge and skill that allowed Bach to bring us The Brandenburg Concertos, or Einstein to offer the Theory of Relativity, or Rafa Nadal to win nine French Opens. It starts almost as a blank slate that develops and evolves by experiencing and learning from the world around it.
So too does the auditory or hearing system. Even in the womb the auditory system begins its development when hearing sounds from the mother as well as sounds that come through from the outside. By about the 24th week of gestation, the ear and cochlea, the organ that receives sound and sends it to the brain, are fully formed and ready to transmit! The auditory pathways of the nervous system start growing and developing and by 42 weeks of gestation the baby can hear sounds as soft as a normal hearing adult can. But things don’t stop there.
If the baby hears “normally,” or hears the soft sounds we are meant to hear, and there is no disruption of the transmission of sound to the brain, then we can use our experiences with sound to “grow” our ability to understand and use sound to develop verbal speech and language, and to know the world we live in. Every time a new sound is heard it gets identified, compared to other sounds we know, paired with the other experiences going on at the same time, including how we feel, and we try to figure out its meaning. Then we decide if it is meaningful to us. If so, how meaningful? Should we remember it or not? Is it something to categorize as fearful, or happy, and what makes it so? Etc., etc. That is a lot for one little baby’s brain to do, yet that is only with hearing! Other senses are bringing in other information at that same time.
If there is a disruption in the auditory system, either with the peripheral system, which is the ear and its sensory organ (hearing loss), or with the central auditory system, or the nerves going from the ear to the brain and the hearing centers in the brain with their connectors (central auditory processing disorder), development of speech and language, as well as other cognitive, social and behavioral skill development can be affected. Nowadays, almost every baby born in the United States has a hearing screening as a newborn. This catches many children who have a hearing loss at birth. Some children do not develop their hearing problems until later however. This may be due to illness, heredity, ear infections, or accident. And, of course, some hearing losses are missed at birth. Other children may have a disruption of the central auditory pathways causing a “listening” difficulty, which does not show up on a hearing test, and may very well not be noticeable until the children are older and exhibit speech/language, cognitive, social and/or behavioral problems.
Speech and language are learned most easily in the first three years of life. So, the earlier any of these difficulties is identified, the less delay there is in “growing” the neural connections that help a child to listen and understand in a classroom, read a book, or tell his parents how his day went.
Most importantly, not only is the brain astounding in its complexity and capability, but in its ability to grow throughout our lives! So, that means that even if we do miss some experiences or learning due to hearing loss or a processing disorder, we can work our brains to get stronger, and we can give them a little help with assistive devices, even if the problem is found later in life.
Many hearing and listening problems cannot be fixed medically or surgically, but we can help most of them with devices, like hearing aids, cochlear or bone-anchored implants, or personal listening systems. These devices can make sounds louder so they can be heard, and/or make speech clearer so it can be more easily understood. They help a child hear and understand throughout the day. Sometimes two devices are used in school or when a child is first learning speech and language (hearing aid and listening system) because those are such critical times for learning. Once the devices are in place, therapies can help a child to recapture some of those missed experiences and teach their brains new ways of listening and thinking and doing. Hearing and speech/language therapy are most useful for helping children with hearing and listening difficulties, but occupational and behavioral therapies are often beneficial too.
Children of any age can have their hearing tested, even very young children. And, children of any age should have their hearing tested if a concern arises, even older ones who have been tested before. Concerns might be a noticeable lack of awareness of sounds, a speech/language delay, behavior problems, misunderstandings, intolerance of or confusion in noise, or learning and listening issues in school.
Hearing happens in the ear, listening happens in the brain. Learning how, or growing your brain, happens fastest when you are young so it is best to catch any hearing or listening problems early. But a brain never stops growing if you give it the right training, so any time is the right time to find out how your auditory system works, and to make listening and learning easier.
Better Speech and Hearing: The Auditory System
Carol Maynard, Doctor of Audiology
