The two types of wave

2. The two types of wave

3. Sound is longitudinal

4. Sound is made by vibrations Vocal chords in the throat

5. Sound travels through the air Ear drum Sound source

6. Displaying sound - oscilloscope

7. Low pitch Low frequency

8. Medium pitch

9. High pitch High frequency

10. Quiet • Turn down the volume on your system Small amplitude

11. Loud Turn up the volume on your system Big ampltitude

12. Loudness and Pitch • Pitch is controlled by frequency – high frequency waves make a high pitch sound. • Loudness or volume is controlled by amplitude – large amplitude waves make a loud sound.

13. Loudness and decibels The loudness of a sound is measures in decibels. If you stand near to these • Silence - 0 dB • A whisper - 15 dB • Normal conversation - 60 dB • A car engine - 90 dB • A car horn - 110 dB • A rock concert or a jet engine - 120 dB • A gunshot or firework - 140 dB

14. Loudness and decibels • Any sound above 85 dB can cause hearing loss. • Eight hours of 90-dB sound can cause damage to your ears • Exposure to 140-dB sound causes immediate damage (and causes actual pain

15. Ultrasound • Humans can hear sounds ranging from a frequency of about 20Hz up to 20 000Hz depending on their age and other factors • Sound of frequency higher than this is called ultrasound. • Ultrasound can be heard by some animals • Many uses have been found for Ultrasound.

16. Range of hearing of some animals

17. Ultrasound reflection The reflection of ultrasound enables distances to be measured. transducer Reflections here

18. Ultrasound scan system

19. Ultrasound image

20. Ultrasound distance measurement

21. Bat navigation