Auditory canal – passage that connects the pinna to the eardrum. Auditory nerve – nerve that sends sounds to the brain. Cochlea – snail shaped organ that changes vibrations into electrical signals. Eardrum – thin sheet of skin that receives sound vibrations. Ear wax – sticky substance in ears. Eustachian tube – passage that connects the middle ear to the throat. Hammer, anvil, stirrup – three small bones in the ear. Inner ear – area of ear where vibrations are changed into signals. Middle ear – area of the ear from the eardrum to the oval window. Oval window – thin sheet of skin at the entrance to the inner ear. Pinna – floppy outer part of the ear. Semicircular canals – three tubes that help the body keep its balance. Things you will learn: How a sound wave gets heard The part of the outer, middle and inner ear The causes of motion sickness Have you ever… Had your ears pop when riding in an airplane? Felt dizzy and lost your balance? Heard your own voice on a recording?
Hearing
The ears are an organ responsible for hearing and helping you keep your balance. They hear sounds thanks to the vibration, or back and forth movement, of sound waves. When an object moves, or vibrates, the vibrations travel through the air as sound waves. These sound waves vibrate the eardrum. Then, these vibrations pass through all the parts of the ear. The cochlea, a snail shaped organ inside the ear, changes the vibrations into electrical signals that go to the brain. The ear is divided into three parts: the outer ear, the middle ear, and the inner ear.
Outer ear
Sounds enter the outer ear first. The part of the outer ear you see on the side of your head is called the pinna. It acts like a funnel for sound waves and is made of cartilage. The pinna collects sound waves and directs them into the auditory canal. The auditory canal is a tube that connects the pinna to the eardrum, Sound waves travel through this tube to the middle ear. The auditory canal is protected by tiny hairs, or cilia, and by ear wax. Ear wax is produced in special glands near the ears. The hairs and wax trap dust and other dirt, keeping them away from the delicate eardrum.
Middle Ear
The middle ear contains the eardrum and three very small bones. After sound waves travel down the auditory canal, they reach the eardrum. The eardrum is a thin sheet of skin stretched over the end of the auditory canal. When the eardrum begins to vibrate, it vibrates the hammer. This causes the anvil and the stirrup to vibrate. These bones act as levers to increase the size of the vibrations to the sound waves don’t fade away as they travel through the ear. The stirrup is the smallest bone in the body. It is less than 0.1 inch long. The eustachian tube connects the middle ear to the back of your throat. The job of the eustachian tube is to make sure the pressure inside your middle ear is equal to the pressure outside your ear. Whey your ears feel stuffed up in an airplane, the air pressure inside your ears is different than outside your ears. The “pop” you feel is the movement of air through the eustachian tube to make the two pressures equal.
Inner Ear
The inner ear is where the vibrations created by sound waves are changed into the electrical signals that your brain interprets. The stirrup (the third small bone) vibrates the oval window, which is the entrance to the inner ear. The vibrations of the oval window create waves in the liquid inside the cochlea. Movement of the liquid causes tiny hairs inside the cochlea to bend. As the hair cells bend, neurons send electrical signals to the brain through the auditory nerve. The semicircular canals are also in the inner ear. They are three little circle-shaped tubes. The semicircular canals help you keep your balance, but they do not help you hear. The three canals are at right angles to each other. One canal is parallel to the ground. A second canal is parallel to the side of the head, and a third canal is parallel to the face. As you move your head, the canals let you sense movement in three ways; up and down, side to side, and backwards and forward. The inner ear plays a major role in helping you keep your balance. Messages from other parts of the body, like the eyes and muscles, are also sent to the brain. The brain uses all this information to adjust your muscles to help keep you balanced. Sometimes, the brain gets messages confused when people are riding in moving vehicles, such as a boat or airplane. When this happens, people may feel dizzy and get an upset stomach. These are symptoms of motion sickness. Sometimes a person can get motion sickness when trying to read in a moving car. The eyes don’t see anything moving because they are focused on the page, but the semicircular canals in the inner ear sense the movement of the car. The brain is confused, and the person can get sick. Most of the time, motion sickness will go away then the movement stops. If it does not go away on its own, people can go to their doctors and get help with the symptoms.
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Funny voices
Many of us don’t like to listen to ourselves on a tape or recorded message. You may think your voice sounds funny when you hear the message, but your friends probably think it sounds like it always does. When we talk, the inner ear received sound in two ways. First, sound waves moving through the air vibrate the eardrum. Second, vibrations of those same sound waves travel through the bones in our head. When we hear our own voices on a recording, we are only receiving sound waves through the eardrum. That’s why it sounds different to us, but not to others.
Label the parts of the ear: anvil cochlea pinna stirrup hammer auditory nerve ear drum semicircular canals eustachian tube ear canal
Each of the following statements is incorrect. Under the statement, write the correct statement. 1. You use your eyes to hear. 2. Sound is made by the vibrations of light waves. 3. The pinna is made from bone. 4. The cochlea is protected by tiny hairs and ear wax. 5. The eardrum vibrates two very large bones. 6. The tibia, the ulna, and the elbow are the three smallest bones in the body. 7. Vibrations become electrical signals in the outer ear. 8. Five semicircular canals help you keep your balance. 9. The cochlea is shaped like a frog. 10. When you hear yourself talk, sound waves travel through the air and through the bones in your head.
Directions: Wr1te the answer that fits each description in the blanks. Use the numbers under the answers to fill in the letters in the question at the end and then answer the question.Answer on your worksheet.
1. Connects the middle ear to the throat 2. The entrance to the inner ear 3. Snail shaped organ that changes vibrations into electrical signals 4. Nerve that carries messages to the brain 5. Three tubes that help the body keep its balance 6. The part of the outer ear made of cartilage. It can hold an earring. 7. The entrance to the middle ear 8. These cause ear parts to vibrate 9. Oval window + cochlea + auditory nerve 10. Pinna + auditory canal Question: Use the letter from the answers above to fill in the blanks and then answer the question. Where can you find the Where can the ____________________, _____________________ and _____________________ be found? Answer: _______________________________________