subject: How does hearing work? [print this page] How does hearing work? How does hearing work?
The ear is an incredibly complex part of the human body that enables numerous bodily functions, from communication with one another to balancing while walking. A hearing impairment, or deafness, is often the term used when one of the functions in the ear breaks down and makes it harder for the brain to receive information passed via sound waves. Hearing impairments are some of the most common birth defects in the world, affecting roughly 3% of babies born, and the number suffering gets larger as people get older and the body starts to break down. But what are those steps that can break down? How is the ear supposed to function? What are the steps between someone talking and another understanding what they are saying? Below is a simplistic guide to how a person hears.
The ear can be separated into three different sections: the inner ear, the middle ear, and the outer ear. The outer ear, the pinna, in medical terms, catches sound waves and funnels them in towards the middle and inner ears. If a sound comes from behind you the pinna reflects it through the ear canal in a different way than if it would have come from in front of you, which is how your brain translates where a noise is coming from. Many hearing aids can help this step by directing and amplifying incoming sound vibrations to make the next step easier on the body.
Once the sound wave breaches the pinna and moves further in the ear towards the eardrum, a tiny membrane that blocks the canal. The often talked about but rarely understood eardrum vibrates as the sound waves hit it and moves three tiny bones on the other side if it, which help the sound to continue the journey towards the brain. The eardrum is the only sensory receptor along the entire hearing process, the rest of the outer, middle, and inner ear is only set up to simply pass along the information received in the eardrum. Curiously, the eardrum also works as your first line of defence against potentially damaging sounds; when the brain recognises harmful sound waves such as high pitch noises, it will send a message to the eardrum to become more ridged, thereby preventing the noise from harming you.
The bones moved by the eardrum, or the ossicles, help to amplify the sound as it moves towards the cochlea, which conducts sound through fluid. Because the sound waves themselves are not strong enough to move through the fluid in your inner ear, the ossicles help to give it some extra force to move through this next step.
The cochlea is gifted with the most interesting part of the hearing process, converting the physical sound waves into electrical terms that the brain can understand. It is incredibly complex, but the vibrations basically move through the different parts of the cochlea until they hit a receptor that corresponds with the vibration, sending electrical impulses to the brain telling it what the vibrations mean. The brain then decodes the impulses and the process is complete.
If any of these steps break down, a person will experience hearing loss, leading to a life of big numbers on the volume controls and the common reoccurrence of the phrase "pardon?". Many problems are avoidable or correctable with the help of modern technology, so be sure to visit a hearing specialist if you suspect any kind of hearing loss.
