SO: v6 (Second Timers)

AN EAR-EE JOURNEY:   If you were to shrink and go into an ear and go down the ear canal,  the first thing you would run into is the eardrum.  The eardrum is a springy “wall” made of cartilage.

AN EAR-EE JOURNEY: If you walked down the ear canal, you would be surrounded by a side-wall and floor with thick ear wax all over it. If you kept going down the ear canal, you would eventually reach the ear drum. The eardrum is a bouncy piece of skin.  We likened it to a trampoline.

AN EAR-EE JOURNEY: Beyond the eardrum wall of skin, there are 3 bones, the hammer anvil and stirrup. The three bones are connected to each other by tendons and ligaments. These three ear bones are the smallest in the body, about the size of two periods on a page.

AN EAR-EE JOURNEY: The three bones of the inner ear, the hammer, anvil and staples are in an airy cavern. The staples bone is a bit like a stirrup on a horse’s saddle. The cavern is directly behind your eyes. (Research if you need to. Be very careful.)

AN EAR-EE JOURNEY: The third bone of the inner part of the ear, the stirrup. has a little bone plate at the end of it.   It hits this “bone plate” against a membrane of the cochlea called the oval window. (Research if you need to.)

AN EAR-EE JOURNEY: The cochlea is fluid-filled. It is about the size of Roosevelt’s head on a dime.  If you uncurled the cochlea so you could see inside it, you’d see there are 3 chambers.  The middle chamber is where the endolymph is housed.  The cochlea is shaped like an abalone shell.

AN EAR-EE JOURNEY:  Bundles of tiny “hairs” line the chamber of the middle membrane.  When the stirrup hits the cochlea wall on the oval window, the fluid in the middle layer vibrates.

AN EAR-EE JOURNEY: The “hairs” that are at the wide beginning part of the cochlea are stiffer than the “hairs” where the cochlea narrows toward the center of it. The vibration of the middle of the cochlea is very important because it moves these microscopic hairs. The taller, stereocilia hairs have “ropes” that are much too small for us to see with the unaided eye. These “ropes” are attached to shorter stereocilia.

AN EAR-EE JOURNEY: When the hair bundles sway in the endolymph fluid, the lid on the connected “hair” is closed… kind of like the lid of a coffee pot is “closed”. When it is closed, potassium ions flow inside the stereocilia “hair”. This causes the sending of a message to your brain that you heard something.

AN EAR-EE JOURNEY: The up and down motion of the little teapots lids and the inflow of ions is what enable you to hear. But, you don’t really hear sounds from anything. All you are doing is opening and closing the “teapots’ lids” of the stereocilia and ions are flowing in as a result. This happens because the endolymph fluid is moving in the rhythm of the sound vibrations that travel in your ears. The sounds you hear are made up by your brain. (Part of this question you have to deduce.)