Chapter 7 of 8

All 8 chapters
  1. 1Sounds come from vibrations, readunderstood
  2. 2Sound travels, readunderstood
  3. 3Echoes, readunderstood
  4. 4A string telephone, readunderstood
  5. 5Loud and quiet, readunderstood
  6. 6High and low notes, readunderstood
  7. 7How we hear, readunderstood
  8. 8Noise and our ears, readunderstood

S2.7.7 Chapter 7

How we hear

How does sound get from the air into your head?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

  • Point to the outer ear, ear canal and eardrum on a drawing
  • Explain how vibrations travel to the eardrum

A drum beats far away. You hear it. How does the sound get into your head?

Look at the side of a friend's head. The part you see is the outer ear. It collects sound and leads it in.

An ear seen from the side, labelled outer ear. An arrow labelled sound points toward the ear from the front.outer earsound
The outer ear collects sound.

Inside the outer ear is a tube. It is the ear canal. The sound goes along it.

Sound in the air is air that shakes. The shaking air goes down the ear canal.

At the end of the canal is a thin piece of skin. It is the eardrum. The shaking air makes the eardrum vibrate.

Draw it first

Draw the way into the ear

  1. A cutaway of an ear. A wide funnel on the left is labelled outer ear. A tube leads from it to the right and is labelled ear canal. A thick black bar across the end of the tube is labelled eardrum. Arrows go in through the funnel and along the tube to the eardrum.outer ear

    1 Draw a wide funnel. Write outer ear.

  2. A cutaway of an ear. A wide funnel on the left is labelled outer ear. A tube leads from it to the right and is labelled ear canal. A thick black bar across the end of the tube is labelled eardrum. Arrows go in through the funnel and along the tube to the eardrum.outer earear canaleardrum

    2 Draw a tube from the funnel. Close its end with a thick bar. Write ear canal and eardrum.

  3. A cutaway of an ear. A wide funnel on the left is labelled outer ear. A tube leads from it to the right and is labelled ear canal. A thick black bar across the end of the tube is labelled eardrum. Arrows go in through the funnel and along the tube to the eardrum.outer earear canaleardrum

    3 Draw arrows going in along the tube to the eardrum.

The eardrum shakes three tiny bones. They pass the shake on to the inner ear.

The inner ear sends messages along a nerve. A nerve is like a thin cable. The messages go to your brain. Then you hear the drum.

A cutaway of the way sound goes in, from left to right. A wide funnel on the left is labelled outer ear. A tube leads from it and is labelled ear canal. A thick black bar across the end of the tube is labelled eardrum. Three small boxes in a row are labelled three tiny bones. A circle at the end is labelled inner ear. An arrow leaves it, labelled nerve. Arrows show the sound going in.ear canalthree tiny bonesouter eareardruminner earnerve
The way sound goes in, from the outer ear to the nerve.

See it three ways

As a picture

Six boxes in a column, with an arrow pointing down between each pair. From the top the boxes are labelled: outer ear, ear canal, eardrum, three tiny bones, inner ear, nerve to the brain.outer earear canaleardrumthree tiny bonesinner earnerve to the brain

In words

Sound goes in at the outer ear and along the ear canal. It shakes the eardrum and the tiny bones. A nerve carries messages to the brain.

Try it

Collect more sound

You need: a friend who talks softly, a quiet room, your hand.

  1. Sit in a quiet room. Your friend sits in front of you, a few steps away.
  2. Your friend talks softly. Listen with your hand down.
  3. Cup your hand behind one ear. Push the ear forward a little.
  4. Listen to the same soft voice again. Is it louder?

What you will see: With your hand cupped, the voice is a little louder. Your hand collects more sound and leads it into your ear canal.

If you cannot try it, this is what happens.
A table with the headings Hand and You hear. Its rows are: down, quiet; and cupped, louder.HandYou heardownquietcuppedlouder

A wrong idea many people have

The outer ear does the hearing.

Why it feels right: The outer ear is the part you see. We say we hear with our ears.

The test that breaks it: Cup a hand behind your ear. Sounds in front get a little louder. Your hand did not hear anything. It only helped the outer ear collect more sound. Now press the front flap of your ear over the hole. Do not push anything in. Sounds go much quieter, but the outer ear is still there. The sound must get in to be heard.

What is true: The outer ear collects sound. The eardrum shakes. A nerve sends messages to the brain. That is how you hear.

Key words

outer ear
the part of the ear you see. It collects sound.
ear canal
the tube that leads sound into the ear.
eardrum
thin skin at the end of the ear canal. It vibrates when sound reaches it.
inner ear
the part deep inside the ear. It sends messages along a nerve to the brain.

Back to your guess

The answer is B: Sound shakes the eardrum, and a nerve tells the brain.

Sound reaches the eardrum and makes it vibrate. The shake goes on, and a nerve sends messages to the brain.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Look at the picture. Which part is the eardrum?

    A cutaway of an ear. A wide funnel on the left is labelled P. A tube leads from it to the right and is labelled Q. A thick black bar across the end of the tube is labelled R. Arrows go in along the tube. Labels: P, Q, R.PQR
    Tap your answer.

    1. Not this one. Part P is the wide funnel. It is the outer ear, and it collects sound. Try another.

    2. Yes, that is right. Part R is thin skin at the end of the ear canal. It vibrates when sound reaches it.

    3. Not this one. Part Q is the tube. It is the ear canal. The eardrum is at its end. Try another.

    See the answer

    Part R

    Part R is thin skin at the end of the ear canal. It vibrates when sound reaches it.

    • If you chose A: Part P is the wide funnel. It is the outer ear, and it collects sound.
    • If you chose C: Part Q is the tube. It is the ear canal. The eardrum is at its end.

  2. What carries sound along the ear canal?

    Tap your answer.

    1. Yes, that is right. Sound in the air is air that shakes. The shaking air goes along the canal to the eardrum.

    2. Not this one. The nerve is deeper in. It carries messages after the eardrum has shaken. Try another.

    3. Not this one. The tiny bones are behind the eardrum. The canal comes first. Try another.

    See the answer

    Air that shakes

    Sound in the air is air that shakes. The shaking air goes along the canal to the eardrum.

    • If you chose B: The nerve is deeper in. It carries messages after the eardrum has shaken.
    • If you chose C: The tiny bones are behind the eardrum. The canal comes first.

  3. Ravi cups his hand behind his ear. Sounds in front get louder. Why?

    Tap your answer.

    1. Not this one. A hand makes no sound. It only collects more of the sound that is there. Try another.

    2. Not this one. The hand does not hear. It leads more sound to the outer ear. Try another.

    3. Yes, that is right. The cupped hand works like a bigger outer ear. More sound is led into the ear canal.

    See the answer

    His hand helps collect more sound.

    The cupped hand works like a bigger outer ear. More sound is led into the ear canal.

    • If you chose A: A hand makes no sound. It only collects more of the sound that is there.
    • If you chose B: The hand does not hear. It leads more sound to the outer ear.

  4. From an earlier chapter

    Why can sound not cross empty space, where there is no air?

    Tap your answer.

    1. Not this one. Speed is not the reason. Sound needs air, water or a solid to pass it on. Go to S2.7.2. Try another.

    2. Not this one. Cold is not the reason. With no air, nothing carries the vibration. Go to S2.7.2. Try another.

    3. Not this one. Size is not the reason. Sound needs air, water or a solid to pass it on. Go to S2.7.2. Try another.

    4. Yes, that is right. Sound passes on through air, water and solids. Empty space has none of these.

    See the answer

    There is nothing to pass the vibration on.

    Sound passes on through air, water and solids. Empty space has none of these.

    • If you chose A: Speed is not the reason. Sound needs air, water or a solid to pass it on. Go to S2.7.2.
    • If you chose B: Cold is not the reason. With no air, nothing carries the vibration. Go to S2.7.2.
    • If you chose C: Size is not the reason. Sound needs air, water or a solid to pass it on. Go to S2.7.2.

  5. Mei says the outer ear does the hearing. What is true?

    Tap your answer.

    1. Not this one. The outer ear collects sound. Hearing happens when messages reach the brain. Try another.

    2. Not this one. The eardrum only vibrates. It passes the shake on. Try another.

    3. Yes, that is right. Sound shakes the eardrum and the bones. A nerve then sends messages to the brain.

    See the answer

    The outer ear only collects sound. Messages go to the brain.

    Sound shakes the eardrum and the bones. A nerve then sends messages to the brain.

    • If you chose A: The outer ear collects sound. Hearing happens when messages reach the brain.
    • If you chose B: The eardrum only vibrates. It passes the shake on.

  6. Draw the way sound goes in. Write outer ear, ear canal and eardrum.

    See the answer

    A wide funnel for the outer ear. A tube for the ear canal. A thick bar at the end for the eardrum. Arrows go in along the tube.

    Sound goes in at the outer ear and along the canal. It makes the eardrum vibrate.

  7. Look at the picture. Which part is the inner ear?

    A cutaway of the way sound goes in, from left to right. A tube is labelled Q. A thick black bar across its end is labelled R. Three small boxes in a row are labelled T. A circle at the end is labelled S. Labels: Q, R, T, S.QRTS
    Tap your answer.

    1. Not this one. Part T is the three tiny bones. They pass the shake on to the inner ear. Try another.

    2. Not this one. Part Q is the ear canal. It leads sound to the eardrum. Try another.

    3. Not this one. Part R is the eardrum. It is thin skin at the end of the canal. Try another.

    4. Yes, that is right. Part S is the inner ear. It gets the shake from the tiny bones.

    See the answer

    Part S

    Part S is the inner ear. It gets the shake from the tiny bones.

    • If you chose A: Part T is the three tiny bones. They pass the shake on to the inner ear.
    • If you chose B: Part Q is the ear canal. It leads sound to the eardrum.
    • If you chose C: Part R is the eardrum. It is thin skin at the end of the canal.

  8. Sipho feels something stuck in his ear. What should he do?

    Tap your answer.

    1. Yes, that is right. The eardrum is thin and can be hurt. Never push anything into the ear. Ask for help.

    2. Not this one. Never push anything into your ear canal. The thin eardrum can be hurt. Try another.

    3. Not this one. Something stuck in an ear should not be left there. A grown up or health worker can take it out safely. Try another.

    See the answer

    Ask a grown up or a health worker for help.

    The eardrum is thin and can be hurt. Never push anything into the ear. Ask for help.

    • If you chose B: Never push anything into your ear canal. The thin eardrum can be hurt.
    • If you chose C: Something stuck in an ear should not be left there. A grown up or health worker can take it out safely.

Keep it

Copy this into your exercise book.

The outer ear collects sound. It goes along the ear canal. The eardrum shakes. Tiny bones pass the shake on. A nerve sends messages to the brain.

Draw: A funnel and a tube with a thick bar at the end. Write outer ear, ear canal and eardrum.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

No internet tomorrow? Save the whole book as one file (610 KB). It opens on any phone.