How does the ear work?
The human ear performs many tasks: It transforms sounds so the brain can process them. And it helps us to tell up from down. Not until our ears stop doing their usual job, for example when we are ill, do we notice what we are missing. This video will focus on the middle ear.
We will explain briefly the different parts that make up the ear, and how sounds are sent to the brain. We will also let you in on what the terms cochlea, hammer and anvil are all about.
The ear is not only a sense organ for picking up sounds. The ear also contains the organ of balance: it helps us to orientate ourselves in space and to direct complex movements.
What you can see of the ear from the outside is only the simplest part, called the auricle. The larger and more complex part of the ear reaches deep into the inside of the head.
The ear is made up of three parts:
- The outer ear includes the auricle, the auditory canal and the outer part of the eardrum. The outer ear is a funnel for collecting sound waves and carrying them to the eardrum.
- The middle ear is a space filled with air that is made up of these parts: the eardrum, the tympanic cavity between the eardrum and the inner ear, where the ear bones – the hammer, anvil and stirrup – are located and the auditory tube – also called the Eustachian tube – which connects the middle ear to the nose and throat area.
- The inner ear is located deep inside the skull, and basically consists of two parts: the vestibule, where the organ of balance is located, and the fluid-filled cochlea: it contains the sensory cells that convert sound waves to nerve signals and then send them on to the brain. Due to its complex system of canals the inner ear is often described as a labyrinth.
The stretched eardrum separates the outer auditory canal from the middle ear and has an important role in the process of hearing: Sound waves from the outside environment set it into vibration. The eardrum transfers these vibrations to the bones of the ear. These bones are arranged as a readily moveable lever, which then amplifies the vibrations and carries them on to the inner ear. The eardrum also prevents dirt and germs from entering the middle ear.
The auditory tube connects the middle ear to the nose and throat area, making sure that, on the one hand, fluid that is constantly produced by the middle ear can be released. On the other hand, air can flow in and out through the auditory tube between the middle ear and the throat. This makes it possible to regulate the pressure between the middle ear and the outside environment.
You feel this regulation in action when, for example, you are in an elevator quickly going downwards or you are sitting in an airplane shortly before landing and your ears pop. Air flows through the auditory tube to the middle ear. This causes your ears to “pop” because pressure on the eardrum is relieved. Without regulation too much or too little pressure can develop in the middle ear, making the eardrum bend in or out – you do not hear as well and all sounds are heard as if they were muffled.
But the auditory tube does have one disadvantage: When you have a cold, for example, it allows germs from the nose and throat area to enter the middle ear, where they can cause an infection. Babies and young children still have a very short auditory tube. This makes it easier for germs to enter the middle ear from the nose and throat area. Once these germs arrive there, they can cause a painful inflammation, which is quite common in young children.
Photos: Thinkstock: www.thinkstockphotos.de
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