Sound lesson 1, Year 8

1. 7 March 2010 Sound Target: To understand what we have to do to an object in order to produce a sound

3. The objects in the pictures are producing sounds. How does each object produce the sound? Next Return Previous Press buttons to hear the sounds again. Sound 1 Sound 2

4. The objects in the pictures are producing sounds. How does each object produce the sound? Next Return Previous Press buttons to hear the sounds again. Sound 1 Sound 2

5. The objects in the pictures are producing sounds. How does each object produce the sound? Next Return Previous Press buttons to hear the sounds again. Sound 1 Sound 2

7. How sound travels… As we know, sound waves are formed when something vibrates. But how does the sound reach our ears? Air molecules 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

8. Studying sound Signal generators can produce signals over a range of frequencies and of varying amplitudes. Loudspeakers convert the signal from the signal generator into sound waves. The oscilloscope allows us to study the frequency and loudness of a sound.

10. Pitch (or frequency)  A high pitch sound .  A low pitch sound. The shorter/longer the wavelength of the wave on the trace; the lower/higher the frequency of the sound. The more waves you can see, the higher the pitch/frequency.

11. Oscilloscope traces Which trace represents the highest pitched sound? A B ‘ A’ is the highest pitched sound because it has the shortest wavelength/most number of waves visible.

13. Sound : What can I hear? Increase the frequency of the signal provided by a signal generator whilst keeping the volume the same. The lowest frequency I can hear is ________ Hz The highest frequency I can hear is __________ Hz 20 20 000

14. Sound : We are not all the same. You have just found your hearing range - could everyone hear exactly the same frequencies as you? We all have slightly different hearing ranges but almost 1 in 5 people suffer some sort of hearing loss. This changes with age. A baby has a wider range than an older person. Temporary hearing loss may be caused by ear infections and colds and hearing recovers. Permanent hearing loss and deafness can be present at birth or occur if the ear is damaged or diseased.

15. Sound : Are we all the same? Hearing is tested using an audiometer and the results are shown on an audiogram. GOOD HEARING POOR HEARING Hearing Loss [dB]

16. Sound : Hearing Ranges Animal Which animal can hear the lowest frequency? pigeons Which animal can hear the highest frequency? moths

17. human cat dog bat dolphin elephant The hearing ranges of different animals. 225 200 175 150 125 100 75 50 25 0 Frequency of sound in kHz