Year 9 - Science
Hearing sound
Waves
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores the nature of sound and water waves, including transverse and longitudinal motion, wave reflection, superposition, and the speed of sound in various media. It covers sound production, detection, and auditory ranges, emphasising data interpretation, and basic calculations.
Lesson Summary
You will learn to explain how sound waves cause sounds to be heard, and describe the range and limits of human hearing.
Key Notes
- Sound waves cause our eardrums, tiny bones within our ears, and the cochlea to vibrate.
- Specialised cells in the cochlea sense vibrations and cause electrical signals to be sent to the brain along a nerve.
- The brain creates the sensation of hearing a sound when it receives signals from the ear through a nerve.
- Human ears can detect sound waves with frequencies between 20 Hz and 20 kHz, being most sensitive to 2–5 kHz waves.
- Sound waves below 20 Hz are called infrasound; above 20 kHz, ultrasound. They are not detected by human ears.
Vocabulary To Learn
- sound wave: a 'pulse' that travels through a material, caused by forward and backward vibrations of particles
- eardrum: a membrane within the ear that is caused to vibrate by incoming sound waves
- sound: a sensation of hearing something
- amplitude: a measure of how far particles vibrate in a sound wave
- frequency: the number of vibrations each second
Common Mistakes To Avoid
- Sound waves are the same thing as the sound heard. Sound waves somehow 'have' sound.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Sound waves cause our eardrums, tiny bones within our ears, and the cochlea to vibrate. Specialised cells in the cochlea sense vibrations and cause electrical signals to be sent to the brain along a nerve.
2. Define this scientific word and use it in context. 'sound wave'
a 'pulse' that travels through a material, caused by forward and backward vibrations of particles. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Sound waves are the same thing as the sound heard. Sound waves somehow 'have' sound. Correction: Distinguish between the sound heard and the sound wave. The brain creates the sensation of hearing a sound when it receives nerve signals from the ear. The sound (heard) does not exist until created by the brain. Sound waves themselves have no sound.
More Lessons In This Unit
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