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 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 Hz Hz Hz
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 Cellphone Real-life
Cell phone Real-life Real-Life
Everything Cell 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 produced Courtesy of howstuffworks.com
440Hz note Real-Life Cell phone
Why? Human hearing range is 12Hz-20000Hz Humans hear best from Hz Cell phone Real-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