1. Properties of Sound Making Waves

2. Sound Waves ■Sound is created by vibrations

3. Sound Waves ■Sound is created by vibrations ■Vibrations move air molecules near them

4. Sound Waves ■Sound is created by vibrations ■Vibrations move air molecules near them ■Molecules forced together, raise air pressure

5. Sound Waves ■Sound is created by vibrations ■Vibrations move air molecules near them ■Molecules forced together, raise air pressure ■Pressure is transferred to other molecules

6. Sound Waves ■Sound is created by vibrations ■Vibrations move air molecules near them ■Molecules forced together, raise air pressure ■Pressure is transferred to other molecules ■This causes a ‘Wave of Pressure’.

8. ■Zero line is pressure of air at rest 0 line High Low

9. ■Zero line is pressure of air at rest ■High points represent higher pressure 0 line High Low

10. ■Zero line is pressure of air at rest ■High points represent higher pressure ■Low points represent lower pressure 0 line High Low

11. ■Amplitude - change in pressure from a wave’s highest point, to it’s lowest point Amplitude Cycle

12. ■Amplitude - change in pressure from a wave’s highest point, to it’s lowest point ■Cycle - refers to the time it takes for the wave to go from one amplitude, through all its changes...to the same amplitude again. Amplitude Cycle

13. ■Frequency - the number of cycles per second

14. ■One Hertz - equals ONE cycle per second ■1000 Hz = 1000 Cycles per second.

15. ■Sound is converted to electrical energy and sent through wires

16. ■For transmission, sound is converted to electrical energy and sent through wires

17. ■Analog - recorded on cassette tape as changes in magnetic strength

18. ■For transmission, sound is converted to electrical energy and sent through wires ■Analog - recorded on cassette tape as changes in magnetic strength ■Digital – recorded and stored on a hard drive as a ‘file’.

19. ■Analog Recordings - sample the wave forms at peaks and valleys

20. ■Digital Audio - samples the sound and turns it in to 1's and 0's

21. ■Analog Recordings - sample the wave forms at peaks and valleys ■Digital Audio - samples the sound and turns it in to 1's and 0's ■The higher the sample rate the greater the number of sampling points per second

22. ■Analog Recordings - sample the wave forms at peaks and valleys ■Digital Audio - samples the sound and turns it in to 1's and 0's ■The higher the sample rate the greater the number of sampling points per second.

23. ■Lower sampling rates do not capture the true sound being recorded

24. ■Sampling rate must be at least TWICE the frequency

25. ■Lower sampling rates do not capture the true sound being recorded ■Sampling rate must be at least TWICE the frequency ■Therefore if frequency is 8000Hz... the sampling rate must be at least 16,000 times per second

26. ■Lower sampling rates do not capture the true sound being recorded ■Sampling rate must be at least TWICE the frequency ■Therefore if frequency is 8000Hz... the sampling rate must be at least 16,000 times per second ■A CD recording is sampled 44,000 times per second.

27. 2 Identical Sound Clips (Grey) Sampled at 2 different rates (Blue)

28. Audio Task ■Open the Voice Recording Assignment sheet in the Handout Folder. Read and practice the printed short story ■Using one of the USB Microphones in the classroom, record the short story in your computer and then Export it as an MP3 file to your Broadcasting Folder.