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2. Hearing The Ear and Vibrations Hearing Range of Humans and Animals Pitch and Frequency Frequency Measured in Hertz (Hz) Effects of Loud Sounds on Hearing
Year 8 • Physics
Hearing
This lesson explains how we hear sound, how the ear works using vibrations, what pitch and frequency mean, how animals hear differently from humans, and why loud sounds can damage hearing.
Lesson Objectives
- Understand how the ear detects sound using vibrations.
- Describe the hearing range of humans and animals.
- Explain pitch using frequency.
- Understand frequency and the unit hertz (Hz).
- Explain how loud sounds affect hearing.
1. The Ear and Vibrations
Hearing happens when sound waves enter our ears and cause vibrations.
These vibrations are detected by the ear and sent to the brain.
Main Parts of the Ear:
• Outer ear – collects sound
• Middle ear – amplifies vibrations
• Inner ear – changes vibrations into nerve signals
• Outer ear – collects sound
• Middle ear – amplifies vibrations
• Inner ear – changes vibrations into nerve signals
Real-life connection:
When you cover your ears, less sound enters, so vibrations are weaker and the sound seems quieter.
2. Hearing Range of Humans and Animals
Different animals can hear different ranges of sound frequencies.
Hearing Ranges:
• Humans: about 20 Hz to 20,000 Hz
• Dogs: can hear much higher frequencies
• Bats: hear ultrasonic sounds for echolocation
• Humans: about 20 Hz to 20,000 Hz
• Dogs: can hear much higher frequencies
• Bats: hear ultrasonic sounds for echolocation
Curiosity moment:
Dogs can hear whistles that humans cannot hear at all.
3. Pitch and Frequency
Pitch tells us how high or low a sound is.
Pitch depends on the frequency of the sound.
• High frequency → high pitch (whistle, bird sound)
• Low frequency → low pitch (drum, thunder)
• Low frequency → low pitch (drum, thunder)
Real-life example:
A small guitar string makes a higher-pitched sound than a thick one.
4. Frequency and Hertz (Hz)
Frequency is the number of vibrations per second.
• Frequency is measured in hertz (Hz)
• 1 Hz = 1 vibration per second
• 1 Hz = 1 vibration per second
Example:
A sound with frequency 500 Hz vibrates 500 times every second.
5. Effects of Loud Sounds on Hearing
Very loud sounds can damage hearing.
• Loud sounds damage tiny hair cells in the ear
• Damage can be permanent
• Long exposure is more harmful than short exposure
• Damage can be permanent
• Long exposure is more harmful than short exposure
Real-life safety:
• Listening to music too loudly with headphones
• Standing near speakers at concerts
• Firecrackers and machinery noise
Practice Questions
A. Fill in the Blanks
- Sound is detected using __________.
- Pitch depends on __________.
- Frequency is measured in __________.
- Humans can hear sounds above __________ Hz.
- Loud sounds can cause __________ hearing loss.
B. True or False
- The ear works using vibrations.
- Dogs hear fewer sounds than humans.
- High pitch means high frequency.
- 1 Hz means one vibration per second.
- Hearing damage can always be repaired.
C. Short Answer
- Name the three main parts of the ear.
- What is pitch?
- Why can dogs hear whistles we cannot?
- What is frequency?
- Give two examples of loud sounds.
D. Real-Life Thinking
- Why should headphones not be used at high volume?
- Why do babies cry at high-pitched sounds?
- Why do bats use sound to find food?
- Why does thunder sound low-pitched?
- Why are ear defenders used in factories?
✅ Show Answer Key
A. Fill in the Blanks
- vibrations
- frequency
- hertz
- 20,000
- permanent
B. True or False
- True
- False
- True
- True
- False
C. Short Answer
- Outer ear, middle ear, inner ear.
- How high or low a sound is.
- They hear higher frequencies.
- Number of vibrations per second.
- Concerts, firecrackers (any two).
D. Real-Life Thinking
- To prevent hearing damage.
- High frequencies are uncomfortable.
- They use echolocation.
- Thunder has low frequency vibrations.
- To protect ears from loud noise.
© Aviate Learning – Hearing (Year 8)