3.46 Sense of Hearing

Hearing is processed through ears in humans but can also be processed by other body parts in other animals. Learn about hearing and discover the parts of the ear, the importance of vibrations, and a condition that affects hearing.

Why Is Hearing Important?

Singing along to your favorite song on the radio. Hearing your best friend’s voice on the phone. Listening to your teacher explain something new and fascinating to you. These are all experiences that require a sense of hearing. Not only does a sense of hearing allow us to communicate, enjoy music, and learn new things, it also keeps us safe by warning us of danger, like when you hear a fire alarm or a car coming down the street.

How Do Humans Hear?

Basically, hearing is the process in which you pick up sound and attach it to meaning. Scientifically speaking, sound travels to us in invisible waves that are created by air vibrations. Vibrations are very small and quick movements that go back and forth, like ocean waves or a string moving up and down. Once the vibrations enter your ear, they are sent to your brain to make meaning out of them so that you can understand the sound.

Your ears are divided into three parts: the outer ear, the middle ear and the inner ear. Your outer ear is made up of the fleshy part that you see, the ear canal, and the drum. The vibration travels through the ear canal, which is like a passageway to the eardrum. When sound waves hit your eardrum, it vibrates, just like a real drum vibrates when it’s hit with a drumstick. If a sound is way too loud, it might burst your eardrum, which would hurt or destroy your sense of hearing.

Part of your eardrum is also in the middle ear, which has tiny bones that vibrate. The movements cause a reaction in the inner ear, which has fluid and teeny, tiny hairs. These hairs are on what looks like a snail shell, called the cochlea. The hairs take the vibration and turn it into an electric signal. That signal sends messages to your brain to let it know that you just heard a sound and the brain needs to tell you what it means.

1. Main points:

Hearing is crucial for communication, enjoyment, learning, and safety. Sound is picked up as vibrations and processed by the ear, which is divided into the outer, middle, and inner ear. The inner ear converts vibrations into electrical signals sent to the brain for interpretation.

2. Questions:

• Content Analysis: What is the importance of hearing and how does it function in humans?
• Contextual Analysis: How do the different parts of the ear contribute to the process of hearing?
• Linguistic Analysis: What words in the text describe the process of sound traveling and being interpreted by the ear?

3. Further Discussion:

How does the ability to hear impact our daily lives and interactions with the world around us?

4. Answers:

• Content Analysis: "Hearing allows us to communicate, enjoy music, learn new things, and keeps us safe… sound travels to us in invisible waves… vibrations enter your ear, they are sent to your brain."
• Contextual Analysis: "The outer ear… ear canal, and the drum… middle ear… has tiny bones that vibrate… inner ear… has fluid and teeny, tiny hairs… cochlea."
• Linguistic Analysis: Words like "vibrations," "travel," "eardrum," "vibrate," "electric signal," and "interpret" describe the process of sound traveling and being interpreted by the ear.

How Do Animals Hear?

While many animals hear with their ears just like humans, some animals hear in a different way. Snakes, for example, only have an inner ear. Therefore, they use the bones of their skull to hear sounds. Snakes will lay their skull and jaw on the ground to feel the vibrations in order to hear. Some insects, like cockroaches and spiders, use tiny hairs on their legs to hear sounds.

Deafness

There are people who are unable to hear sounds. The inability to hear is known as deafness. While deafness means that the person is unable to hear the way that other people do, this does not mean they are not able to communicate. Helen Keller, for example, is one of the most inspirational women of all time. She was deaf and blind, but this didn’t stop her from going to college, writing books, and being a role model.

Deafness is not always permanent. Inventors and doctors have created devices that can help. Some deaf people choose to wear cochlear implants that allow them to hear. If someone has a hard time hearing but is not completely deaf, hearing aids can help them hear sounds.

1. Main points:

Animals have varied hearing mechanisms, with some using bones or hairs to detect vibrations. Deafness, the inability to hear, doesn’t prevent communication, and can sometimes be mitigated with devices like cochlear implants or hearing aids.

2. Questions:

• Content Analysis: How do different animals hear and what is deafness in humans?
• Contextual Analysis: How do alternative hearing mechanisms in animals compare to human hearing?
• Linguistic Analysis: What words in the text describe the ways animals hear and the condition of deafness?

3. Further Discussion: How does understanding different hearing mechanisms in animals help us appreciate the diversity of sensory experiences in nature?

4. Answers:

• Content Analysis: "Snakes… use the bones of their skull to hear sounds… Some insects… use tiny hairs on their legs to hear sounds… Deafness is the inability to hear."
• Contextual Analysis: Snakes and some insects have adapted unique ways to hear, different from the typical ear-based hearing in humans.
• Linguistic Analysis: Words like "vibrations," "bones of their skull," "tiny hairs," "deafness," and "cochlear implants" describe the ways animals hear and the condition of deafness.

Lesson Summary

We are able to hear sound waves when they vibrate, or shake quickly, against the eardrum, which is part of your outer ear. The vibration travels first through your outer ear, which is made up of the fleshy part that you see, the ear canal, and the eardrum. The vibration travels through to the middle ear, which has tiny bones that vibrate, causing movements in the inner ear, which has fluid and teeny, tiny hairs. These tiny hairs send signals that your brain interprets into the sound you hear. When someone has no sense of hearing, this is called deafness. A sense of hearing helps us to do many things in our lives and understand the world around us.