Hearing is how we perceive sound. It's how our ears take sound waves and turn them into something our brain can understand.
There are three major parts of the ear that help us to hear:
Why two ears?
- The outer ear - The outer ear has three sections:
- The pinna or auricle: this is the part of the ear on the outside of our heads. The part we usually are referring to when we say ear. It helps to gather sound and vibrations so we can hear more sounds.
- The ear canal: This is a tube that helps sound to travel further inside our ear and to get to the next stage of hearing
- The eardrum: The eardrum is a thin sheet that vibrates when the sound hits it. Your eardrum is very sensitive and fragile. It's never a good idea to put anything in your ear, even something that seems safe and soft can damage your eardrum.
- The middle ear - The middle ear is filled mostly with air and has three bones in it. That's right your ear has little bones called ossicles that help you hear! They are called the hammer (malleus), anvil (incus), and stirrup (stapes). They amplify the sound or make it louder. The middle ear helps to transfer sounds from the air to fluid inside the next stage, or inner ear. The stirrup is the smallest bone in the body.
- The inner ear - The inner ear is filled with fluid and has the hearing organ called the cochlea. This organ helps to take the vibrations and translate them into electrical signals for the nerve to send to the brain. It actually uses little hairs that vibrate with the sound waves in the fluid. Then you "hear" it. Amazing! The inner ear also has fluid filled tubes that help with your balance.
Having two ears helps you to determine the direction of sound. Your brain is smart enough to figure out that if sound hits one ear just before the other and is slightly louder then that's the direction the sound came from. Having an ear on each side of our head also helps us to hear better.
The Frequency of Sound
We can hear sound within a certain frequency range of around 20 Hz on the low end and 20,000 Hz on the high end. Some animals have different ranges. Dolphins, for example, can't hear sounds as low as we can, but can hear high sounds of over 100,000 Hz. Dogs and cats can hear much higher pitched sounds than we can.
Why do I get dizzy?
The brain takes in a number of signals from your body to keep it balanced. One of them is from the fluid in the inner ear. The brain can tell a lot by how the fluid in your ear is moving or tilted. The brain also uses your eyes and sense of touch to tell it about your balance and position. When you spin really fast and then stop, the fluid in your ear is still spinning, but your eyes and body have stopped moving. Your brain gets confused for a bit and you feel dizzy.
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