1. Cell Phone Effect on Sounds Caleb “Raising the Bar” __________ Max “The World’s Largest 3G Network” __________

2. Purpose  To use Fourier Analysis to compare a real-life sound to a sound filtered through a cell phone

3. Our Software: Audacity A free, open-source digital audio editor

4. Tests 0.Nothing (control) 1. Caleb note 2. Piano low 3. Piano medium 4. Piano high 5. Tuba Mouthpiece 6. “background noise” 7. Background conversation 8. Caleb voice 9. Max voice 10. 440Hz 11. 3520Hz 12. 4000Hz

5. Test #1: Caleb’s Voice Cellphone Real-life

6. Test #1: Caleb’s Voice Cellphone Real-life

7. Caleb’s Voice, Zoomed In (.04 second) Cellphone Real-life

8. Analyzing the Data

9. Caleb’s Note, Frequencies Spectrum Cellphone Real-life

10. Cell phone Real-life Real-Life

11. Everything Cell phone Real-life

12. Our Findings  Intermediate frequencies added  Frequencies dropoff at 5000 Hz

13. Background Conversation Real-Life Cell phone

14. 440Hz note Real-Life Cell phone

15. Max’s Voice Real-Life Cell phone

16. Audacity’s Fast Fourier Transform

17. #1 FFT uses condensed Fourier Series So we know this: And also this:

18. So we can do this: So we know this: And also this:

19. How Cell Phones Work  Cell phones are radios!  Cell phones convert analog signal to digital signal and send the digital signal to the cell tower picture credits: wikipedia

20. Converting from Analog to Digital  The soundwave is sampled every fraction of a second  In this process, frequencies are lost  A lower-resolution sound is produced Courtesy of howstuffworks.com

21. 440Hz note Real-Life Cell phone

22. Why?  Human hearing range is 12Hz-20000Hz  Humans hear best from 1000-5000Hz Cell phone Real-life

23. Conclusion  Cell phone reduces sounds above 5000Hz  Cell phone adds intermediate frequencies

24. The End

25. Audacity’s Fast Fourier Transform

26. Sample Size Does Not Matter

27. Audacity’s Fast Fourier Transform Thanks UMich!

28. #2 “Fourier Transformation is a Linear Operation” “ The transform of a constant times a function is that same constant times the transform of the function” Quoted from Numerical Recipes in C, p497