Chapter 6 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

S2.7.6 Chapter 6

High and low notes

Why can one rubber band make high and low notes?

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

  • Make high and low notes with water bottles or stretched rubber bands
  • Explain that faster vibrations make higher notes

A mouse squeaks. A lion roars. The squeak is high. The roar is low.

A note is a steady sound you can sing or hum. The pitch of a note is how high or low it is.

Every note comes from a vibration. What makes one note higher than another? It is how fast the thing shakes.

Draw it first

Draw a low note and a high note

  1. Two pictures of a rubber band and its sound wave. The top wave is labelled low note and has 2 waves. The bottom wave is labelled high note and has 7 waves. Both waves are the same height. The words 2 waves and 7 waves are written beside them.low note

    1 Draw a slow wave with a few bumps. Write low note.

  2. Two pictures of a rubber band and its sound wave. The top wave is labelled low note and has 2 waves. The bottom wave is labelled high note and has 7 waves. Both waves are the same height. The words 2 waves and 7 waves are written beside them.low notehigh note

    2 Draw a fast wave with many bumps, the same height. Write high note.

  3. Two pictures of a rubber band and its sound wave. The top wave is labelled low note and has 2 waves. The bottom wave is labelled high note and has 7 waves. Both waves are the same height. The words 2 waves and 7 waves are written beside them.low notehigh note2 waves7 waves

    3 Count the bumps. Write 2 waves and 7 waves.

The two waves are the same height. So they are equally loud. The high note has more bumps in the same space.

More bumps means more shakes in the same time. A high note shakes fast. A low note shakes slowly.

A low note might shake 100 times in one second. A high note might shake 1 000 times.

A rubber band shows this well. Stretch it across a box and pluck it. Now stretch it tighter. The note goes higher.

A tight band shakes faster. A thin band shakes faster than a thick one. A short band shakes faster than a long one.

Two strings, each stretched between two posts and equally tight. The top string is long and labelled long string. Its dashed lines show it shaking. It is labelled low note. The bottom string is short and labelled short string. It is labelled high note.long stringlow noteshort stringhigh note
A short string shakes faster, so its note is higher.

Big things shake more slowly. Two drums are made the same way. The big one gives the lower note.

Bottles of water make notes too. How you make the sound matters. Say which one you did.

See it three ways

As a picture

Two bottles side by side. The left bottle has a little water and is labelled little water. The right bottle has more water and is labelled more water. Below them is a table with the headings You and More water. Its rows are: tap it, a lower note; and blow across, a higher note.little watermore waterYouMore watertap ita lower noteblow acrossa higher note

In words

Tap the bottles. The one with more water gives a lower note. Blow across the tops. The one with more water gives a higher note.

When you tap, the bottle and the water shake. More water is harder to shake. So it shakes slower, and the note is lower.

When you blow across the top, the air inside shakes. More water leaves less air. Less air shakes faster, so the note is higher.

Try it

Make high and low notes

You need: a rubber band, a small open box, or a tin with no sharp edges.

Be safe: Keep the box away from your face. Stretch the band only until it is tight. Never stretch it until it might snap.

  1. Stretch the rubber band across the open top of the box.
  2. Hold the box away from your face. Pluck the band. Listen to the note.
  3. Stretch the band a little tighter. Pluck it again. Is the note higher or lower?
  4. Press one finger on the middle of the band. Pluck one half. What do you hear?

What you will see: A tighter band gives a higher note. A shorter band gives a higher note. Both shake faster. Pluck with the same strength each time, so you hear the change.

If you cannot try it, this is what happens.
A table with the headings Band and Note. Its rows are: loose, lower; tight, higher; half length, higher.BandNotelooselowertighthigherhalf lengthhigher

A wrong idea many people have

More water in a bottle always makes a lower note.

Why it feels right: Most people tap the bottles first. Then more water does give a lower note.

The test that breaks it: Stand two glass bottles side by side. Put a little water in one and more in the other. Tap each with a spoon, gently. Then blow across the top of each, not into it. Listen each time. The order of the notes turns round.

What is true: It depends how you make the sound. Tap: more water gives a lower note. Blow across: more water gives a higher note.

Key words

note
a steady sound you can sing or hum.
pitch
how high or low a note is.

Back to your guess

The answer is D: It shakes faster for a high note.

A band that shakes faster makes a higher note. A band that shakes slower makes a lower note.

Check yourself

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

  1. Lucía stretches a rubber band tighter and plucks it. What happens to the note?

    Tap your answer.

    1. Not this one. A tighter band shakes faster, not slower. A faster shake makes a higher note. Try another.

    2. Not this one. A tighter band changes how fast it shakes. A louder sound needs a bigger pluck. Go to S2.7.5. Try another.

    3. Yes, that is right. A tight band shakes faster. Faster vibrations make a higher note.

    See the answer

    It gets higher, because the band shakes faster.

    A tight band shakes faster. Faster vibrations make a higher note.

    • If you chose A: A tighter band shakes faster, not slower. A faster shake makes a higher note.
    • If you chose B: A tighter band changes how fast it shakes. A louder sound needs a bigger pluck. Go to S2.7.5.

  2. Look at the picture. Which rubber band gives the higher note?

    Two pictures, P and Q. Each shows a rubber band and its sound wave. The wave in P has 2 bumps. The wave in Q has 7 bumps. Both waves are the same height. Labels: P, Q.PQ
    Tap your answer.

    1. Yes, that is right. Q has more bumps in the same space. It shakes faster, so its note is higher.

    2. Not this one. P has fewer bumps. Fewer bumps means slower shakes and a lower note. Try another.

    3. Not this one. Both waves are the same height, so they are equally loud. But Q has more bumps, so its note is higher. Try another.

    See the answer

    Band Q

    Q has more bumps in the same space. It shakes faster, so its note is higher.

    • If you chose B: P has fewer bumps. Fewer bumps means slower shakes and a lower note.
    • If you chose C: Both waves are the same height, so they are equally loud. But Q has more bumps, so its note is higher.

  3. Tariq gently taps two glass bottles with a spoon. One has more water. Which gives the lower note?

    Tap your answer.

    1. Not this one. Less water is lighter to shake. So tapping it gives the higher note. You may be thinking of blowing across the top. Try another.

    2. Yes, that is right. More water is harder to shake. It shakes slower, so the note is lower.

    3. Not this one. The water changes how fast the bottle shakes. The two notes are different. Try another.

    See the answer

    The bottle with more water

    More water is harder to shake. It shakes slower, so the note is lower.

    • If you chose A: Less water is lighter to shake. So tapping it gives the higher note. You may be thinking of blowing across the top.
    • If you chose C: The water changes how fast the bottle shakes. The two notes are different.

  4. Ana blows across the tops of two bottles. One has more water. Which gives the higher note?

    Tap your answer.

    1. Not this one. Less water leaves more air. A bigger space of air shakes slower, so the note is lower. You may be thinking of tapping. Try another.

    2. Not this one. The water changes how much air is left to shake. The two notes are different. Try another.

    3. Not this one. Blowing harder makes a louder sound, not a higher note. The air left in the bottle sets the note. Try another.

    4. Yes, that is right. More water leaves less air. Less air shakes faster, so the note is higher.

    See the answer

    The bottle with more water

    More water leaves less air. Less air shakes faster, so the note is higher.

    • If you chose A: Less water leaves more air. A bigger space of air shakes slower, so the note is lower. You may be thinking of tapping.
    • If you chose B: The water changes how much air is left to shake. The two notes are different.
    • If you chose C: Blowing harder makes a louder sound, not a higher note. The air left in the bottle sets the note.

  5. From an earlier chapter

    Mei plucks a rubber band hard, not softly. What happens to the note?

    Tap your answer.

    1. Not this one. A bigger move makes a louder sound, not a higher note. Go to S2.7.5. Try another.

    2. Yes, that is right. The size of the move changes the volume. How fast the band shakes changes the note.

    3. Not this one. A hard pluck does not change the note. It changes the volume. Go to S2.7.5. Try another.

    See the answer

    It stays the same, and the sound is louder.

    The size of the move changes the volume. How fast the band shakes changes the note.

    • If you chose A: A bigger move makes a louder sound, not a higher note. Go to S2.7.5.
    • If you chose C: A hard pluck does not change the note. It changes the volume. Go to S2.7.5.

  6. Draw the waves for a low note and a high note. Make both the same height.

    See the answer

    The low note wave has a few bumps. The high note wave has many bumps. Both are the same height.

    A high note shakes faster. So more bumps fit in the same space.

  7. Look at the picture. Hana plucks both strings. They are equally tight and thick. Which gives the higher note?

    Two strings, each stretched between two posts. The top string is long and is marked P. The bottom string is short and is marked Q. Labels: P, Q.PQ
    Tap your answer.

    1. Not this one. More length makes a string shake more slowly. A long string gives a lower note. Try another.

    2. Not this one. Length changes how fast a string shakes. A short string shakes faster. Try another.

    3. Yes, that is right. The short string shakes faster, so its note is higher.

    See the answer

    String Q

    The short string shakes faster, so its note is higher.

    • If you chose A: More length makes a string shake more slowly. A long string gives a lower note.
    • If you chose B: Length changes how fast a string shakes. A short string shakes faster.

  8. Ravi has two drums made the same way. One is big and one is small. Which gives the lower note?

    Tap your answer.

    1. Yes, that is right. A big drum shakes more slowly than a small one. A slower shake gives a lower note.

    2. Not this one. A small drum shakes faster, so its note is higher. Big things shake more slowly. Try another.

    3. Not this one. Size changes how fast the skin shakes. The big drum shakes slower, so its note is lower. Try another.

    See the answer

    The big drum

    A big drum shakes more slowly than a small one. A slower shake gives a lower note.

    • If you chose B: A small drum shakes faster, so its note is higher. Big things shake more slowly.
    • If you chose C: Size changes how fast the skin shakes. The big drum shakes slower, so its note is lower.

Keep it

Copy this into your exercise book.

A faster vibration makes a higher note. A tight, thin or short band gives a higher note. Tap bottles: more water gives a lower note. Blow across: more water gives a higher note.

Draw: A wave with few bumps and a wave with many bumps. Write low and high.

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.