Sensory System Series: Auditory System
What is your favorite sound? A few that come to mind for myself are birds chirping, baby’s laughing, and waterfalls. These sounds are calming and fill me with joy. On the other hand, I can’t stand the sound of nails on a chalkboard. We all have sound preferences based on how our auditory system functions.
The auditory system is our sense of hearing or our ability to perceive sounds to interpret the world around us. We are able to listen, observe, and make connections by receiving sensory information through our ears. We are born with this basic skill. In fact, the development of auditory skills begins in the womb and is the sense to become functional.
This system works closely with our vestibular system as the receptors of both are hair cells. The auditory stimulus are sound waves that enter the ear and cause the eardrum and bones of the middle ear to vibrate. These vibrations of tiny hair cells in the inner ear convert the vibrations into electrical signals which are sent to the brain by the auditory nerve to be processed. Our system hears sounds which are a series of pressure changes in the air. Sounds often vary in frequency and intensity over time. In order for us to hear sounds, it has to be above a certain level called a hearing threshold. We humans have a hearing threshold of 0 decibels which is the measurement for sound pressure level. Sounds above 90 decibels can result in hearing damage. Thresholds can vary among individuals therefore one sound may be very loud to one person, but quiet to another. The same goes for being able to work in a busy environment versus a quiet environment.
Our ears have a vital role in many skills that are needed to function. The ear holds hair cells, the receptors of our auditory and vestibular system, impacting healing, balance, flexibility, bilateral coordination, speaking, breathing, social interaction, and academic learning. Specifically, hearing is essential for communication, language, and interaction. It is also a protective mechanism to keep us safe in our environment and can influence our emotions.
There are two components of the auditory systems functioning: defensive and discriminative. As babies, we start with a defensive system with loud and new sounds being startling. Our brains develop the ability to modulate (regulate, process) auditory sounds to inform us if it is enjoyable or one we should avoid. Our brains learn to habituate or become accustomed to sounds.The first time a balloon pops at a birthday party is very startling, however, our reaction becomes less startling after a third balloon pops. Another example of this is students working in a quiet classroom on a math assignment. The overhead light is buzzing interfering with one student's ability to concentrate while another student is able to habituate or tune out the sound to continue working. As auditory skills develop, our ability to listen does as well. We learn to distinguish sounds and listen to understand their meaning. The discriminative component of the auditory system improves as children explore and engage in multisensory experiences.
Below are discriminative functions that help us understand the “what” and “where” of sounds to help us function:
Localization: ability to identify the source of a sound and judge the distance between the sound and oneself.
Tracking: the ability to follow a sound.
Auditory memory: the ability to remember what was heard.
Auditory sequencing: the ability to put in order what was heard and repeat it in logical order.
Auditory discrminiation: the ability to compare and contrast environmental sounds.
Auditory figure-ground: the ability to distinguish between foreground and background sounds.
Association: the ability to relate a novel sound to a familiar sound and relate a visual symbol with a particular sound.
Auditory cohesion: the higher level listening ability to unite various ideas into a coherent whole (understand riddles, jokes, puns, take notes in class).
Auditory attention: the ability to maintain focus to listen to what is being said.
A child with sensory processing disorder may have challenges with processing auditory input impacting the above one or more of the skills above. Their auditory system may be over-responsive (hypersensitive) or under-responsive (hyposensitive). Over-responsivity means one has a larger than expected emotional or behavioral response to sensory input. It takes little input to produce a sensation. Auditory over-responsivity, also called auditory defensiveness, means a child is constantly alert and must listen to every sound therefore become easily distracted. They may startle to ordinary noise where their body is constantly on edge and alert. This can hinder their ability to learn and the development of language and social skills.
On the other hand, a child may be under-responsive where the child has low arousal where they don’t notice the sensory input and it takes a lot of input to produce a sensation. A child with auditory under-responsivity seems unaware of sounds that others hear. They don't respond to quiet sounds or soft voices. As our hearing plays a role in communication, the child may speak quietly because they have difficulty detecting the sound level of their voice. A child with sensory processing disorder may also seek intensive auditory input. They love loud things and places, such as crowds, rodeos or car races.
Therapeutic Tool Highlight: Auditory Filtering Headphones
Noise filtering headphones provide noise blockage while still allowing for small amounts of noise to travel through the barrier. Low profile clam design keeps the muffs safe and secure on little ears and offers a stylish look. Strong high quality parts make them sturdy and robust. Lightweight and comfortable to suit little ones. Padded ear cushions offer superior comfort and a snug fit. Foldable for easy storage and portability. Adjustable (just slide the cups up and down the wire frame to adjust), so they fit children as young as six months and as old as grandpa.
Sensitivities of the auditory system can be challenging. We hope the above strategies are helpful and if you need more or have questions, let us know! We are here to support you!
Check out our sensory system handouts you can purchase individually or as a bundle on our website! A great resource to learn about sensory processing disorder and each of our sensory systems. BONUS: print them off and hang them on the wall for all who pass by to view and learn or share with family, friends or teachers for them to have insight into your child’s sensory system.
Photos:
http://www.brainsoundlab.com/research/
https://www.medicinenet.com/can_a_child_outgrow_auditory_processing_disorder/article.htm