1. A Fourier Into the World of Sound MEBBEM feat. Kohl Kohl Coffey Brandon Kearns Michaela Howard Emma Zelus

2. Experiment Basics Description: Using two configurations of speakers and recorders, we will verify the Doppler Effect and analyze air density, sound intensity, and frequency data in order to find a relationship among altitude, air density, and sound waves.

3. Hypothesis Doppler Effect - If a source emits a constant frequency, and the receiver moves away from the source at a sufficient velocity, the received frequency will be smaller than the emitted frequency. Air Density and Sound - With increasing altitude, the density of air decreases. With lower air density, the speed of sound increases along with the frequency of sound.

4. Experiment Method: Doppler Effect On the ground, there was a frequency generator and a large speaker. The speaker emitted a constant frequency. On our balloon, we had a Dan Gibson parabolic dish with a microphone positioned at the focal point of the dish. Connected to the microphone was a recorder that will record the received sound for later analysis. We unravelled the rope attached to the weather balloon so as to achieve the maximum possible constant upwards velocity during our data collection period.

5. Experiment Method: Air Density and Sound The speaker emitted sound at constant frequency and intensity, whilst the recorder merely recorded the sound. When we were ready to commence the launch, we will play the emitted sound and begin recording. The S4 Instrument Kit continuously collected data for pressure, temperature, and position over time. We halted the progress of the balloon at 50, 150, 500, and 1000 feet for 5-10 minutes each in order to allow the S4 Instrument Kit to acclimate and collect consistent data for a considerable time period.

6. Experiment Analysis: Doppler Effect Measured emitted frequency Measured received frequency o FFT Software Measured velocity of receiver Verified, with the measured received frequency data, that the frequency did decrease as the balloon moved farther away Compared the calculated doppler effect (Doppler Equation) with the measured doppler efffect

7. Experiment Analysis: Air Density and Sound Collected data for altitude, y position over time, temperature, and air density using S4 Data. Used FFT Software to analyze change in frequency over time -> compare with altitude Used Sound Analysis Software to analyze change in sound intensity with altitude Analyzed the relationships between altitude, temperature, air density, sound intensity, and sound frequency

8. Data Collection Doppler Effect We gathered data for the frequency with respect to time as the balloon traveled upward We experienced issues with collecting sound data due to malfunctions with cables Air Density and Sound We gathered data for the change in air pressure with respect to altitude We gathered data for the change in frequency with respect to time

9. Analysis and Conclusion

10. Analysis and Conclusion (cont’d) Frequency: constant At 2002 Hz No change in Frequency with respect to air pressure