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Hear ye, hear ye

This article first appeared in the 1/24/20 edition of the Davis Enterprise

Hear ye, hear ye

Human ear anatomy with detailed diagram. Photo by Iain at English Wikipedia, courtesy of Wikimedia Commons

Hear ye, hear ye

 

Sara Thompson

Special to the Enterprise

 

Last week we learned a bit about the human eye and how it works, but our current exhibit is on Light & Sound, so this week’s article is about our ears and how we can hear.  The human ear is made up of 3 main parts, the outer, middle, and inner ear.  All of these parts contain an intricate and specialized system of parts to help us to hear the sounds around us.

 

Before we get to the ear, however, we should mention how sound moves through the air.  When we speak, or when a car horn honks, or a stick breaks, this causes a disturbance on the air molecules and sends vibrations through the air, called sounds waves.  The sound waves are picked up and channeled through our outer ear.  The outer ear begins with the pinna or auricle, which if the visible part that we have on the sides of our head.  The shape helps to capture sound waves and channel them through the ear canal and to the eardrum.  Sound waves bounce off the eardrum and causes it to vibrate, and those vibrations are transferred to the middle ear.

 

The middle ear is simply the area connecting the outer ear to the inner ear but is no less important to the whole system.  It is primarily made up of 3 tiny bones called the malleus, incus, and stapes, and are the smallest bones in the human body, and together are called the ossicles.  The middles ear is an air-filled cavity where these three bones reside, and they vibrate cause from the sound waves interacting with the ear drum.  The vibrations will vibrate a small membrane called the oval window which moves fluid on its other side, which is the inner ear.

 

The inner ear is a fluid filled cavity and is connected to the middles ear by the oval window.  Vibrations from the middle ear move the fluid present in the cochlea.  The cochlea is covered in microscopic cells that look like tiny hairs, or bristles on a brush.  Different bunches of these hair cells react to different sound pitches, which move the fluid of the inner in different ways.  Some hair cells move when the fluid is moving fast, and others when it is moving slow, and this movement is what helps tell our brain what sound it is we are hearing.  As we get older these hair cells break down and die.  When a hair cell dies, it doesn’t regenerate nor can it be repaired, so a loss of a hair cell is a loss of hearing certain pitches.  Higher pitches and frequencies tend to be lost earlier because these hair cells are the first ones to interact with the vibrations of the moving fluid in the cochlea and deteriorate quicker than the lower pitched hair cells.

 

Check out Explorit’s Light & Sound Exhibit and learn more about sound and how it can be manipulated both inside and outside the ear.  We are open to the public on Wednesday, Friday, Saturday, and Sunday from 1-5pm.  Admission is only $5 per person, free for Members, teachers with school ID, ASTC, and ages 2 and under.

 

 

 

 

 

 

Explorit's coming events:

 

 

  • Become a member of Explorit!  Membership grants you free visits to Explorit’s regular public hours, discounts on events, camps, and workshops, and gives you ASTC benefits.  For more information or to purchase or renew your membership visit www.explorit.org/join/membership-levels or call Explorit at 530-756-0191.
  • Enrollment still available for Explorit’s Nature Bowl team.  This is an afterschool science team from students grades 3-6.  Call (530) 756-0191 to register.  The $25 fee covers weekly meetings and a t-shirt.
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