8L 3 – How do We Hear Sounds?

2. 8L 3 – How do We Hear Sounds?

3. How do We Hear Sounds? The Aim of this lesson is for you to know: • That the effects of vibrations to the ear drum are transferred to the brain. • The energy of sound is transferred through the ear drum. • Some animals can detect sounds which are inaudible to human ears. • Different people can hear different ranges of pitch. • Hearing changes with age.

4. 1) An object makes a sound by vibrating 2) The vibrations pass through air by making air molecules vibrate 3) These vibrations are picked up by the ear Recap - How Sound Travels… As we know, sound waves are formed when something vibrates. But how does the sound reach our ears? Air molecules

5. The Ear and Sound Waves

6. The Ear

7. Activity • Using Heinemann pack 2 – p359 draw a flow chart of how we hear sounds into your book. • Use a whole page. • Complete it as we go through the next few slides.

8. How Does the Ear Hear? 1.Sound waves are collected by the ear lobe (or pinna). 4.The small bones (ossicles) amplify the vibrations. 6.The auditory nerve takes the signals to the brain. 6 4 1 2 3 5.The cochlea turns these into electrical signals. 5 2.The waves travel along the ear canal. 3.The waves reach the eardrum and make it vibrate.

9. How does the ear work? 5) The electrical signals are then sent to the brain 1) Sound waves are “funnelled” into the ear by the pinna 4) These vibrations are turned into electrical signals in the cochlea 2) These vibrations make the ear drum vibrate 3) These vibrations make the ear bones vibrate

10. Hearing Range Set the volume and increase the frequency of the signal provided by the signal generator. Humans can only hear sounds of certain frequencies. The range of frequencies a person can hear is called their hearing range. What is the hearing rangeof a healthy young person? 20 Hz to 20,000 Hz

11. Comparing Hearing Ranges

12. Sound Facts and Figures Middle C on a piano 256 Hz Small insect wings 1000Hz Bat calls 130,000Hz Elephant calls 15Hz Sounds above our range of hearing – ultrasonic Sounds below our range of hearing – subsonic Now please complete Sheet L3

13. Hearing Ranges and Hearing Loss Note: Does everyone have the same hearing range? We all have slightly different hearing ranges. People lose the ability to hear sounds of high frequency as they get older. Almost 1 in 5 people suffer some sort of hearing loss. Temporaryhearing loss may be caused by ear infections and colds, after which hearing recovers. Permanenthearing loss and deafness can be present at birth or occur if the ear is damaged or diseased.

14. Practical – Hearing Test! Heinemann 2 Activity L3a Core p286.

15. Sound Facts and Figures Middle C on a piano 256 Hz Small insect wings 1000Hz Bat calls 130,000Hz Elephant calls 15Hz Sounds above our range of hearing – ultrasonic Sounds below our range of hearing – subsonic Now please complete Sheet L3

16. Practical – Making a Model Ear Drum

17. Any Questions ?

18. Missing Words

19. Summary - How do We Hear Sounds? • The effects of vibrations to the ear drum are transferred to the brain. • The energy of sound is transferred through the ear drum. • Some animals can detect sounds which are inaudible to human ears. • Different people can hear different ranges of pitch.

20. Homework / Prep Enter the following in your personal Prep diaries: To be completed by:

21. Next Lesson Can Sound be Dangerous?

22. Any Questions ?

24. The Ear