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TwiddleLab / Physics / Waves and Sound

Pitch and Loudness

Lesson 4 of 10 · 7 min · Free, no account needed

What you will learn

  • Pitch is set by frequency: more waves per second sound higher.
  • Loudness is set by amplitude: taller waves push the air harder and sound louder.
  • People hear roughly 20 Hz to 20 kHz; the top drops with age. Decibels count loudness in steps: +10 dB is 10 times the power.

Start the lesson

How the lesson goes

  1. Some ringtones are so high that many adults can't hear them, but most teens can. What makes a sound high?

    Two sound waves, drawn over the same tiny slice of time.

  2. A tone generator. Play it and turn the frequency.

    Listen to the pitch and watch the wave.

  3. Same pitch, two sounds. Which is louder?

    Amplitude is how far the air is pushed and pulled. A bigger push carries more energy into your ear, and you hear that as loudness.

  4. Two dials of a sound.

    Pitch comes from frequency. Middle C is about 262 Hz, the A above it 440 Hz.

    Loudness comes from amplitude: how big the pressure swings are.

    Young people hear about 20 Hz to 20,000 Hz (20 kHz). The top end drops with age, so a 17 kHz ringtone can be a teen-only sound.

    Decibels (dB) measure loudness in steps: every +10 dB is 10 times the power. Simplified: real loudness also depends on how sensitive the ear is at each pitch.

  5. Game: Match the note. Tune your dial until it sounds like the target.

    Three notes. Your score is the hertz you are off, in total.

  6. Put each sound on the decibel ruler.

    These are typical values. Loudness falls the further you are from the source, so a real street or concert can be a bit quieter or louder.

  7. Math: a scale where equal steps multiply. How much more power is a concert than talking?

    dB = 10 × log₁₀(power ratio). So each +10 dB adds 1 to the exponent: 60 dB is 10⁶, 110 dB is 10¹¹, and 10¹¹ ÷ 10⁶ = 10⁵.

  8. Here is your first note from the game. Draw a wave that sounds higher and louder.

    Pitch and loudness are separate dials: frequency changes how often the air is pushed, amplitude how hard.

  9. Back to the ringtone. How high can you hear today?

    Use headphones or speakers at a normal level.

Previous lesson: Sound Is a Pressure Wave · Next lesson: Echoes: Sonar and Ultrasound · Part of the course: Waves and Sound

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