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Cell Phone Effect on Sounds

Cell Phone Effect on Sounds. Caleb “Raising the Bar” __________ Max “The World’s Largest 3G Network” __________. Purpose. To use Fourier Analysis to compare a real-life sound to a sound filtered through a cell phone. Our Software: Audacity. A free, open-source digital audio editor. Tests.

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Cell Phone Effect on Sounds

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  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) • Caleb note • Piano low • Piano medium • Piano high • Tuba Mouthpiece • “background noise” • Background conversation • Caleb voice • Max voice • 440Hz • 3520Hz • 4000Hz

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

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

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

  8. Analyzing the Data

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

  10. Real-Life Real-life Cell phone

  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 know this: And also this: So we can do 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 Real-life Cell phone

  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

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