Chapter 8 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

S2.7.8 Chapter 8

Noise and our ears

Can a noise harm my ears if it does not hurt?

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.

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

By the end you can

  • Test which materials muffle sound best
  • Explain how loud noise can harm hearing and how to protect it

Some noises are too loud. We want them quieter. How can we do that?

To muffle a sound is to make it quieter. You put something round the thing that makes it.

Some things muffle sound better than others. Here is how to test them.

Draw it first

Draw the muffling test

  1. A box on the left holds a clock, labelled clock. A thick wrap round it is labelled cloth. A person on the right is labelled you. An arrow goes from the clock to the person, and the words count steps are written under it.clock

    1 Draw a box for the clock. Write clock.

  2. A box on the left holds a clock, labelled clock. A thick wrap round it is labelled cloth. A person on the right is labelled you. An arrow goes from the clock to the person, and the words count steps are written under it.clockcloth

    2 Draw a thick wrap round the clock. Write cloth.

  3. A box on the left holds a clock, labelled clock. A thick wrap round it is labelled cloth. A person on the right is labelled you. An arrow goes from the clock to the person, and the words count steps are written under it.clockclothyoucount steps

    3 Draw yourself some way off. Draw an arrow to you. Write count steps.

Try it

Which material muffles best?

You need: a ticking clock, or a phone playing a steady alarm, a sheet of paper, a thin cloth, a thick towel, a long clear path.

Be safe: Do not wrap anything that gets warm. Never wrap a phone that is charging. If a phone feels warm, unwrap it at once.

  1. Put the clock on the ground. Start close to it.
  2. Walk away in a straight line. Stop when you cannot hear it. Count your steps.
  3. Wrap the clock in paper. Put it in the same place. Do the walk again.
  4. Do the same with the thin cloth. Then do it with the thick towel.
  5. Which wrap gave the fewest steps? That wrap muffled best.

What you will see: The table shows example numbers. Yours will differ. Thick, soft, fluffy things should give you the fewest steps. Thin paper changes little.

If you cannot try it, this is what happens.
A table. The headings are Wrapped in and Steps. Its rows are: nothing, 10; paper, 8; thin cloth, 5; thick towel, 2.Wrapped inStepsnothing10paper8thin cloth5thick towel2

Thick, soft, fluffy things muffle sound best. They take in the vibrations. Thin paper takes in very little.

Noise is sound we do not want. Some noise is very loud. Think of an engine, a machine or a firecracker.

Very loud noise can harm the tiny parts inside your ear. Your hearing can get worse for ever.

Harm can happen with no pain at all. Harm depends on how loud it is, and for how long.

Ringing in your ears after a noise is a warning. Your ears have had too much.

See it three ways

As a picture

A table with the headings Sound and Can harm?. Its rows are: whisper, no; talking, no; loud engine near, yes; firecracker, yes.SoundCan harm?whispernotalkingnoloud engine nearyesfirecrackeryes

In words

A whisper and talking do not harm your ears. A loud engine near you can. A firecracker can.

Here is how to protect your ears. Move away from the noise. Cover your ears with your hands.

Use ear plugs if you are given them. Ear plugs and ear muffs muffle sound before it reaches the eardrum.

A circle on the left is labelled noise. Three arrows go from it toward an ear on the right, labelled ear. A hatched block in front of the ear is labelled ear muff, and the arrows stop at it. One small arrow gets through.noiseear muffear
Ear muffs stop most of the noise before it reaches the ear.

Keep headphones turned low. If a friend beside you hears your music, turn it down.

A table with two columns, Do this and Result, and four rows. Move away gives less noise. Cover ears gives less sound in. Ear plugs give muffled sound. Music low gives safer ears. Labels: Do this, Result, move away, less noise, cover ears, less sound in, ear plugs, muffled sound, music low, safer ears.Do thisResultmove awayless noisecover earsless sound inear plugsmuffled soundmusic lowsafer ears
Four ways to protect your ears.

A wrong idea many people have

If a noise does not hurt, it cannot harm my hearing.

Why it feels right: When something hurts, we move away from it. So no pain feels like no danger.

The test that breaks it: Never test this with a loud noise. Ask an older person who worked near loud machines for years. Many say it never hurt. Many now hear less, and some hear ringing all the time.

What is true: Loud noise can harm hearing with no pain. Ringing is a warning. Protect your ears before the harm is done.

Key words

muffle
to make a sound quieter.
noise
sound we do not want. Some noise is very loud.

Back to your guess

The answer is D: Yes. Loud noise can harm hearing with no pain.

Very loud noise can harm your hearing for ever. It can do it with no pain at all.

Check yourself

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

  1. Which wrap muffles a sound best?

    Tap your answer.

    1. Not this one. Thin paper takes in very little sound. Thick, soft, fluffy things muffle best. Try another.

    2. Not this one. With nothing round the clock, nothing takes in the sound. Try another.

    3. Yes, that is right. A thick, soft towel takes in the vibrations. You hear less of the sound.

    See the answer

    A thick towel

    A thick, soft towel takes in the vibrations. You hear less of the sound.

    • If you chose A: Thin paper takes in very little sound. Thick, soft, fluffy things muffle best.
    • If you chose B: With nothing round the clock, nothing takes in the sound.

  2. Look at the table. Mei hears the clock from 10 steps with nothing round it. With the thick towel, how many steps fewer?

    A table. The headings are Wrapped in and Steps. Its rows are: nothing, 10; paper, 8; thin cloth, 5; thick towel, 2.Wrapped inStepsnothing10paper8thin cloth5thick towel2
    See the answer

    8 steps

    With nothing, it is 10 steps. With the thick towel, it is 2. So 8 steps fewer.

  3. Joseph's ears ring after a very loud noise. What does it mean?

    Tap your answer.

    1. Yes, that is right. Ringing after a noise warns that it may have harmed his hearing.

    2. Not this one. Harm can happen with no pain. Ringing is the warning. Try another.

    3. Not this one. Loud noise does not make ears stronger. Ringing warns of harm. Try another.

    See the answer

    It is a warning that his ears have had too much.

    Ringing after a noise warns that it may have harmed his hearing.

    • If you chose B: Harm can happen with no pain. Ringing is the warning.
    • If you chose C: Loud noise does not make ears stronger. Ringing warns of harm.

  4. Which is a good way to protect your ears?

    Tap your answer.

    1. Not this one. That adds more noise to your ears. Keep headphones low. Try another.

    2. Yes, that is right. Moving away makes the noise quieter by the time it reaches you.

    3. Not this one. Noise can harm with no pain. Move away. Try another.

    See the answer

    Move away from the noise.

    Moving away makes the noise quieter by the time it reaches you.

    • If you chose A: That adds more noise to your ears. Keep headphones low.
    • If you chose C: Noise can harm with no pain. Move away.

  5. From an earlier chapter

    Why must nothing be pushed into the ear canal?

    Tap your answer.

    1. Yes, that is right. The ear canal ends at the eardrum, which is thin skin.

    2. Not this one. Even gentle pushing can hurt the thin eardrum. Go to S2.7.7. Try another.

    3. Not this one. The canal ends at the eardrum. The tiny bones and inner ear are behind it. Go to S2.7.7. Try another.

    See the answer

    The thin eardrum at the end can be hurt.

    The ear canal ends at the eardrum, which is thin skin.

    • If you chose B: Even gentle pushing can hurt the thin eardrum. Go to S2.7.7.
    • If you chose C: The canal ends at the eardrum. The tiny bones and inner ear are behind it. Go to S2.7.7.

  6. Name three ways to protect your ears from loud noise.

    See the answer

    Move away. Cover your ears or use ear plugs. Keep headphones low.

    Each one makes the noise quieter before it reaches your eardrum.

  7. Look at the picture. Both people stand by the engine for a long time. Whose ears are safer?

    A hatched box on the left is an engine, labelled engine. Two people stand to its right, labelled P and Q. A dashed line from the engine to P is labelled 2 m. A longer dashed line from the engine to Q is labelled 40 m. Labels: engine, P, Q, 2 m, 40 m.enginePQ2 m40 m
    Tap your answer.

    1. Not this one. Ears do not get used to it. Loud noise keeps harming them, and the harm can last for ever. Try another.

    2. Not this one. Harm can happen with no pain. The noise is louder near the engine. P is at more risk. Try another.

    3. Not this one. Quiet sounds do not harm ears. Very loud noise does, and moving away makes it quieter. Try another.

    4. Yes, that is right. The noise is quieter far from the engine. Q gets less of it, so Q's ears are safer.

    See the answer

    Person Q, who is further away

    The noise is quieter far from the engine. Q gets less of it, so Q's ears are safer.

    • If you chose A: Ears do not get used to it. Loud noise keeps harming them, and the harm can last for ever.
    • If you chose B: Harm can happen with no pain. The noise is louder near the engine. P is at more risk.
    • If you chose C: Quiet sounds do not harm ears. Very loud noise does, and moving away makes it quieter.

  8. Diego hears a very loud noise often for years. What may happen to his hearing?

    Tap your answer.

    1. Not this one. Harm from very loud noise does not always heal. It can last for ever. Try another.

    2. Not this one. Loud noise can harm the hearing of anyone, young or old. Try another.

    3. Not this one. Harm can happen with no pain. That is why ears need care before it hurts. Try another.

    4. Yes, that is right. Very loud noise can harm the inside of the ear for good.

    See the answer

    It can get worse for ever.

    Very loud noise can harm the inside of the ear for good.

    • If you chose A: Harm from very loud noise does not always heal. It can last for ever.
    • If you chose B: Loud noise can harm the hearing of anyone, young or old.
    • If you chose C: Harm can happen with no pain. That is why ears need care before it hurts.

  9. Priya listens to music with headphones. A friend beside her can hear the music. What should she do?

    Tap your answer.

    1. Not this one. Louder music for a long time can harm hearing for good. Turn it down. Try another.

    2. Not this one. Loud music for a long time can harm hearing, with no pain. Try another.

    3. Yes, that is right. If a friend can hear it, the music is too loud. Keep headphones low.

    See the answer

    Turn it down.

    If a friend can hear it, the music is too loud. Keep headphones low.

    • If you chose A: Louder music for a long time can harm hearing for good. Turn it down.
    • If you chose B: Loud music for a long time can harm hearing, with no pain.

Keep it

Copy this into your exercise book.

Thick, soft things muffle sound best. Very loud noise can harm hearing for ever, with no pain. Ringing is a warning. Move away, cover your ears, keep headphones low.

Draw: A clock in a thick wrap, an arrow, and a person. Write count steps.

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.