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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. - PowerPoint PPT Presentation
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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
Tests0. Nothing (control)1. Caleb note2. Piano low3. Piano medium4. Piano high5. Tuba Mouthpiece6. “background noise”7. Background conversation8. Caleb voice9. Max voice10. 440Hz11. 3520Hz12. 4000Hz
Test #1: Caleb’s Voice
Cellphone
Real-life
Test #1: Caleb’s Voice
Cellphone
Real-life
Caleb’s Voice, Zoomed In (.04 second)
Cellphone
Real-life
Analyzing the Data
Caleb’s Note, Frequencies Spectrum
CellphoneReal-life
Cell phone
Real-Life
EverythingCell phone
Real-life
Our Findings Intermediate frequencies added Frequencies dropoff at 5000 Hz
Background Conversation
Real-Life
Cell phone
440Hz note
Real-Life
Cell phone
Max’s Voice
Real-Life
Cell phone
Audacity’s Fast Fourier Transform
#1 FFT uses condensed Fourier Series
So we know this:
And also this:
So we can do this:
So we know this:
And also this:
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
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 producedCourtesy of howstuffworks.com
440Hz note
Real-Life
Cell phone
Why? Human hearing range is 12Hz-20000Hz Humans hear best from 1000-5000Hz
Cell phoneReal-life
Conclusion Cell phone reduces sounds above 5000Hz Cell phone adds intermediate frequencies
The End
Audacity’s Fast Fourier Transform
Sample Size Does Not Matter
Audacity’s Fast Fourier Transform
Thanks UMich!
#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