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Cell Phone Effect on Sounds

This study investigates how cell phones affect sound quality by comparing real-life audio to that filtered through a cell phone. Using Audacity, we conducted tests on various sounds, including different musical notes and voices, analyzing frequency response through Fast Fourier Transform (FFT). Our findings reveal that cell phones significantly reduce frequencies above 5000 Hz while adding intermediate frequencies, affecting overall audio clarity. This research highlights the implications of analog-to-digital conversion in mobile communication.

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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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