How your Ear Works

If you ever wanted to know how your ear works....


First off: The reason you are able to tell which direction a sound is coming from is because your ears are separated by your head, and there is a very tiny time delay between sound reaching one ear vs. the other. Your brain interprets this as directionality.


Your ear is subdivided into three sections: outer, middle, inner.


Outer (Pinna!)- This is what you can see. The ridges in your ear help you to locate the sounds in the vertical plane (up/down) and also amplify the frequency of human speech (3000Hz).


Middle When sound travels past your outer to the middle it's going to hit your ear drum, which will smack into your ossicles (lil bones) and then into your stapes.


The stapes is your link to the inner ear (cochlea). It pushes against the top portion of the cochlea.


Inner Your cochlea is a a coiled tube with only one opening. It's about 35mm long when you stretch it out (think of a test tube resting on it's side). The inside of the tube is divided by thin membranes into several subsections. If you think about it very basically, your cochlea has a top half and a bottom half. If you have your cochlea uncoiled, the dividing membrane (basilar membrane) goes almost all the way to to the back of of our cochlea (still think of that test tube), but stops - leaving a small gap called the helicotrema. 


When noise reaches your cochlea it is going to enter through the top section of the cochlea, travel to the end, and make it's way through the helicotrema and come back out your cochlea through the bottom half.


While the air goes into your ear it causes the basilar membrane (which divides the top/bottom sections of your cochlea) to move up and down. Attached to your basilar membrane  is the Organ of Corti, which basically just refers to all the cells that are attached to the basilar membrane - your hair cells. Above the hair cells is a membrane called the tectorial membrane (inside of the top half of the cochlea). Some of the hairs of the hair cells are attached to it, some are not. The motion of the basilar membrane causes the hairs on the top of the hair cells to move up and down, pushing against the tectorial membrane, and the hairs open up a bunch of ion channels. The movement of the ions through these channels is what what tells your brain that you heard something. 

Your ear!

How do we hear at different frequencies?

Think of stringed instruments. stiffer/shorter = higher pitch. Longer/looser = lower pitch. Near the opening of the cochlea (if you stretch it out like a test tube), the hairs on your hair cells are stiffer and shorter - allowing them to pick up high frequency sounds. The hair cells in the back (near the helicotrema) are longer and more flexible, allowing you to pick up lower frequency sounds.

Here's a picture of what your hair cells look like. Hairy, yes?

Fun fact:
If you put a very tiny microphone up to your inner ear, you can hear the sound that entered it coming back out.

Bad Environmental Habits

I would like to say that I am more or less an environmentally conscious person. I recycle, I turn off lights, I try to use up every little bit of material I have when I make crafts...
...but I make a lot of bad environmental decisions too. I drive my car to and from school instead of taking the bus or biking or walking, I take showers that are way too long, and I tend to buy too much food that I end up throwing away.


Public opinion polls repeatedly show that most Americans identify themselves as "environmentalists," but these people are just like me - all for saving the environment, but then they make decisions that are adding to the harm. This is because we all have our vices. We get greedy, we get lazy, we feel that we don't have enough time. We do these things without putting too much thought in to them - it's all habit, really. And if we truly want to do significant good  for the environment - our biggest challenge is going to be breaking these habits.

 Each of us are little bricks in the foundation of our society. We are all in this together... it doesn't make sense to assume the foundation to change if the pieces within do not shift. Every great movement, needs its members to be passionate for the cause. If you want to see improvement, look within yourself and make the sacrifice. And do not get caught up in what everyone else is doing - if you feel strongly for your cause, then the failure of others does not absolve you from your own duties. Every little positive thing we do adds up. Let's try to make it a habit of doing much more good than harm, and just do without as many of our negatives contributions as possible, maybe then we will start to see a shift.