Pennsylvania - Movie Theater Captioning
1. The Cochlea Turns “Sound” into “Hearing”
Sound waves are almost everywhere. But even though your brain is a really amazing organ, it alone isn’t able to recognize sound waves. That’s the job of the cochlea! The cochlea is the innermost part of the ear and connects directly to the brain.When the ear picks up sound vibrations they’re sent through different parts of the ear and into the cochlea, in the same way that a funnel directs liquid. In the cochlea these sound vibrations are turned into little electrical signals that go straight to the brain. Then, the brain’s nerve cells take over and you perceive the sense that we call “hearing.” And all of this happens almost instantaneously.
2. It’s The Size of a Pea
Each cochlea is incredibly tiny. It’s about the size of a pea and from the outside looks like a tiny little snail shell. But inside of this tiny little organ are all sorts of little structures that work together to turn sound into hearing. They’re all rolled up into a spiral, but if you would unroll an average cochlea it would end up being a tube about 31.5mm long. This tube can be a few millimeters wide at the base, but towards the very top it shrinks to mere fractions of a millimeter. Within this small distance is everything that your body needs to turn sound vibrations into hearing.3. There Are Over 20,000 Nerve Cells in the Average Cochlea
Just because it’s tiny doesn’t keep it from being filled with all sorts of special cells. In fact, there are over 20,000 hair cells that are entirely responsible for receiving sound waves and turning them into hearing.Check out the photo at the top of this post to see what they look like: the green parts are just a few of these 20,000 cells. And to give you a sense of scale, each of the green cells is less than 20 micrometers long (0.0007 inches)! The little hairs on the very top vibrate back and forth in response to sound waves, and then these vibrations are turned into electrical signals within the bigger green parts. The yellow parts are part of the auditory nerve, and are like the roads that send these electrical signals straight to the brain.
4. Different Nerve Cells Cause Different Sounds to be Heard
All 20,000 of these cells are spread along the distance of the cochlea, or about 31.5mm. But if you stimulate two different hair cells that are far apart, you would hear two completely different sounds. This happens because of the way that the hair cells are arranged along a membrane within the cochlea. The membrane is short and stiff on one end so it only responds to high-pitched sounds (like a bird’s chirp), while the other end is longer and more flexible so it only responds to low-pitched sounds (like the beat of a drum). This is called “tonotopy,” and it’s so cool that it deserves a story all on its own – more about that another time!5. Fluid Inside the Cochlea Makes Waves
The membrane vibrates, but it doesn’t vibrate in air. Instead, the part of the cochlea that touches these hair cells and the membrane is filled with a special fluid called endolymph. Because this fluid is heavier than air, it moves with more force so that the hair cells and membrane can work more efficiently. It’s a lot like the difference between having a summer breeze in your face and being hit by a strong wave along the beach.(Photo of the Organ of Corti courtesy of R. Glueckert , K. Pfaller, A. Schrott-Fischer, H. Rask-Andersen; Medical University of Innsbruck, Austria)
Have you got a question about the cochlea or do you know something about the cochlea that we haven’t covered?
After years of speech therapy, I still felt totally isolated. Even then I knew that it was not fair that I had to work so hard to learn to speak like a hearing person, only to be isolated by my deafness in social settings.
Sadly, this is a very common experience among hearing impaired people. We often wonder, shouldn’t communication be a two-way street?
I finally got the opportunity in high school to attend a School for the Deaf. Ironically, once I learned American Sign Language, it was then that I felt the least “deaf” and “impaired” than I ever did in the hearing world.
With the communication barriers broken down, I felt like I finally truly belonged somewhere. My personality flourished, and I got to see that while quiet and shy around hearing people, I am vibrant and outgoing around Deaf peers.
Some Deaf people are angry. Only a small percentage of us are born into the Deaf world, the rest have to struggle with our identity and communication barriers throughout our lives.
Growing up, some of us are subjected to years of embarrassing and tedious speech therapy, only to be made fun of for our voices that we worked so hard to acquire.
We master lip-reading, only to be left out of conversations repeatedly. We are given cochlear implants as if it is the cure for all of our woes, yet we still are, and always will be, deaf.
Some of our Deaf peers have been brutally beaten or even killed whenever officers misinterpret our signing as an attempt to resist arrest, or mistake our hard-earned clear voices as a sign that we can actually hear their demands as well.
Some of us have been treated as inconveniences when we pull directly up to the window to order our food or coffee. Some of us have been misdiagnosed with metal health issues we do not have, and in some cases we are given medication for the wrong conditions, locked away in mental health hospitals for years, or denied treatment altogether for conditions we DO have.
This is partially the result of diagnostic tools being designed for patients with spoken language and administered by those who are not well-versed in Deaf culture norms.
Some of us are still denied accommodations or given unqualified interpreters in educational, legal, professional, and medical situations, sometimes with far-reaching or deadly consequences which can change the course of lives and the lives of our loved ones.
We Deaf are less likely to be given leadership roles or denied the jobs we apply for. Yes, some of us are angry.
We are born into a world which we are not completely equipped to fit into, a world designed for those who can hear. Even so, we are amazing.
We are great mothers, fathers, friends, and any other role that can be found in the hearing world. We have a unique perspective on life and a richness of character that comes from our years of struggling with communication barriers and our identity. If only the hearing world could understand this.
The hearing world can do many things to make our world more Deaf-friendly. They can take the time to learn how to accommodate us, and follow through with it. Know that our ability to speak is not always an accurate assessment of how much we can hear.
Police officers and other professional organizations need to make Deaf sensitivity training a part of their core education. Hearing parents of deaf children, help your child find his/her own identity instead of assigning one to them.
At the very least, please do not teach them that those who sign are failures, or that those who choose to learn speech are less Deaf. Take the time to learn about our culture and language. Doing these things is a great start toward making the modern Deaf experience into a more positive one for us.
Jenn Hearn is a Deaf mom of two adorable little boys. She works as an adjunct instructor of ASL and SLI/ASL lab coordinator at University of Cincinnati.
The Limping Chicken is the UK’s deaf blogs and news website, and is the world’s most popular deaf blog.