Can You Hear Me Now?

Materials and Methods: One parabolic sound collecting dish was used with a microphone in the center connected to an IPod Touch with the freqCounter app on. The thermostat was then set on 70°F. The dish was placed 197 cm away from the oven. Then a long “middle C” was played using a tuner metronome at 0, 225, 325, 425, and 450°F. 

Results: The higher temperatures were constantly better than the lower ones. The last variation was a little bit smaller than the second to last one though. Overall there was a big difference between the fist and the last variation.

Conclusions: Higher temperatures do affect how fast the frequency is. The higher the temperature, the more sound is collected.

Type

• Physical Science

Grade

• 7^th-9^th grade

Difficulty of the Project

• Hard

Cost

• $80 (excluding the IPod, tuner metronome and the oven)

Safety Issues

• Gloves should be worn while cutting wood and handling the hot oven.

Time Taken to Complete the Project

• 40 hours

Objective

The project is about how heat and distance affect frequency collected. The goal of this experiment is to see how heat and distance affect the amount of sound collected.

Materials and Equipment

For Dish and Frame

• Iron wok or similar bowl, about 15 ¾ inches in diameter-1
• 4 inch diameter circular fixture box for hanging lamp with 1-inch diameter center hole-1
• Threaded rod-46 cm
• Headset with microphone that is compatible with the IPod Touch-1
• IPod Touch-1
• IPod App- FreqCounter-1
• 3 ½ x 3 ½ x 25cm piece of pine wood-2
• 30 Diameter cm circular piece of ply wood-1
• 3 ½ x 3 ½ x 47cm piece of pine wood-1
• 4 inch atrium grate-1
• ⅜ inch stove bolts and nuts for cabinet hinges-2
• Nuts ¼ inch square and 2 wing nuts ¼ inch-3 each
• Large fender washers 1 ½-inch -4
• 1-inch nails-8
• Corner braces, each with four screw holes-2
• Short wood screws-9
• Stove bolts for pivot seal 2 by 5/16 inches and nuts to fit-2 each
• ¼ inch t-sleave-2

Additional Materials

• Power drill with ¼ and 10/32 bits-1
• Grinding wheel attachment for drill-1
• Hacksaw for fine-tooth material-1
• Tuner Metronome-1
• Oven

The materials were mostly purchased from a hardware store, excluding the tuner metronome, which was purchased at a music store. The materials were readily available. 

Introduction

Sound is a very big part of nature. It is created by objects vibrating, which in turn makes air or another substance in the air to create sound waves, which can be heard. Louder sounds are made from larger vibrations, while softer sounds are created from smaller vibrations. The SI unit to measure frequency is hertz (Hz). Frequency is how many times a wavelength vibrates per second. The average human can hear between 20 and 16,000 Hz. Barometric pressure also affects the frequency of an object. The more barometric pressure present, the higher the frequency.

A parabolic sound collecting dish is a good way to measure the frequency of sound. A parabolic sound collecting dish can be used to listen to distant sound and noises, and measure its frequency. Once the dish is placed in the desired position, the sound will travel through the air and bounce off the dish into the microphone, where the frequency can by recorded. The unwanted sounds bounce off at different angles, so they never reach the microphone.  

Terms and Concepts for Background Research

Sound waves were researched to see if pressure affects the frequency of sound. Barometric pressure was researched in partner with sound waves. Sound was also a big topic and was researched to see how it behaved in different temperatures. Finally, we researched about parabolic sound collecting dishes and how they worked.

Research Questions

• Does heat affect the frequency of sound?
• Does atmospheric pressure affect the frequency of sound?
• Does distance affect how sound is collected?
• How does the frequency of sound behave in different weather conditions?
• How does a parabolic dish work?

1. Assemble the parabolic sound collecting dish (see appendix a).
2. Set the oven to 0^oF with room temperature at 70°F.
3. Place the parabolic sound collecting dish 197 cm away from the oven.
4. Surround all sides of the dish except for the side facing the oven with poster boards so the unwanted sound is kept out.
5. Pl ay one long single “middle C” tone at 440 Hz on the tuner metronome for 15 seconds facing the oven and record the measurement on the IPod on the other side of the poster board.
6. Record the sound in hertz.
7. Repeat this 5 times, label each trial 1, 2, 3, 4, and 5.
8. Repeat steps 2-7 four more times at 225, 325, 425, and 450°F.
9. Repeat steps 2-8, except at 394 cm.

Results

 

The average is 1826.2 Hz. The outlier is trial one because it is 621.8 Hz higher than the average. There is no trend. The range of the data is 1098 Hz.

The average is 3172.2 Hz. The outlier is trial one because it is 1306.8 Hz above the average. There is no trend. The range of the data is 2360 Hz.

The average is 3808.2 Hz. The outlier is trial three; it was 1102.8 Hz higher than the average. There is no trend. The range of the data is 1737 Hz.

The average for the data is 4805.6 Hz. There was no outlier; they are all close to the average. There is no trend. The range of the data is 1575 Hz.

The average of the data is 4643.0 Hz. There was no outlier; they were all close to the average. There is an upward trend and at trial 5 the trend starts to drop. The range of the data is 4808 Hz.

The average of all the trials is 3651 Hz. The outlier was trial one because it is 1824.8 Hz lower than the average. There is an upward trend that slopes down at 450°F. The range of the averages is 2979.4 Hz.

 

The average is 1781 Hz. There is no outlier, they all were very close to eachother.There was no trend, and the range was 416 Hz.

 

The average is 2406 Hz. The outlier was trial four, it is 487 Hz below the average, and there is no trend. The range is 932 Hz.

 

The average is 2634.6 Hz. The outlier is trial 2, because it is the farthest from the average. It is 171.4 Hz above the average. There seems to be no trend, The range is 301 Hz.

The average is 2887.6 Hz. The outlier is trial 2 because it is 355.4 Hz above the average. There is no trend, and the range of the data is 631 Hz.

 The average of the averages is 2247.92 Hz. The outlier is trial one, because it is 717.52 Hz.There is an upward trend going from 0°F to 450°F. the range of the averages is 1357.2 Hz.

Conclusions

The original hypothesis states that at 450°F and at 197 cm, more sound would be collected because sound travels faster in higher pressure. Also, if there is more heat in the air, the higher pressure. The hypothesis was partially correct. At 225°F and at 197 cm, the average sound collected was 1826.2 Hz, and at 450°F and at 197 cm the average sound collected was 4643 Hz. However, at 425°F and at 197 cm, the average sound collected was 4805.6 Hz. All of the averages trials at 394 cm were lower than the ones at 197 cm, the highest being 2887.6 Hz at 450°F. The closer an abject is and the more heat is present allows it to collect more sound. 

Questions for Further Research

Fairness of the Experiment

Not all of the other factors besides the independent variable were controlled. First, the thermostat doesn’t read the temperature in the whole house, so the temperature could have been different then what the thermostat read. Also, the dish could have moved a little from all of the handling it had during the experiment. Third, since the tuner metronome couldn’t be placed in the oven when it heated up, the metronome was in different places in the oven all of the time. If the experiment could have been repeated, a room that could be heated up evenly would have been used. Also, a heat resistant metronome would have been ideal with the parabolic sound collecting dish bolted down. Lastly the container should be sound proof and have the air pressure at sea level.

Other Areas of Interest

1. How does changing the temperature to negative degrees effect sound collection?

            This relates to our experiment because it has to do with how temperature affects the amount of sound collected. If hotter temperatures make the amount of sound collected go up, then cooler temperatures should make the amount collected go down. It would be interesting to see if this is true.

2. How does changing the amount of wind affect the rate of sound collection?  

            This relates to our experiment because the experiment took place in a windless environment. However, the wind outside is always changing, due to differences in air pressure, so the amount of hertz collected might depend on the wind.

3. How does changing the volume (decibels) of the sound effect sound collection?

Decibels and Hertz are related in the sense that they both have to do with sound. Saying this, the amount of decibels given off could affect the amount of Hertz collected.

Bibliography

Websites

Jason, and Samuel. Sound Is Energy. Web. 15 Dec. 2010. <http://library.thinkquest.org/5116/sound.htm>.

Davidson,, By Michael. "The Effects of Low Barometric Pressure on the Ears | EHow.com."EHow | How To Do Just About Everything! | How To Videos & Articles. Web. 15 Dec. 2010. <http://www.ehow.com/list_6011957_effects-low-barometric-pressure-ears.html>.

Weed,, By Geoffrey. "What Is Barometric Pressure? | EHow.com." EHow | How To Do Just About Everything! | How To Videos & Articles. Web. 16 Dec. 2010. <http://www.ehow.com/about_4597603_what-barometric-pressure.html>.

"Speed of Sound." Test Page for Apache Installation. Web. 15 Dec. 2010. <http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe2.html>.

"Sound." Encyclopædia Britannica. 2010. Encyclopædia Britannica Online. 15 Dec. 2010 <http://www.britannica.com/EBchecked/topic/555255/sound>.

"Sound." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica, 2010. Web. 15  Dec.  2010. <http://school.eb.com/eb/article-9109557>.

Adnes, Michael. "Sound Waves." Websters Dictionary. Print.

Books

Vecchione, Glen. "Parabolic Sound-Collecting Dish." 100 Amazing Make-it-yourself Science Fair Projects. New York: Sterling Pub., 2005. 71-75. Print.

Busch-vishniac, Ilene J. "World Book Inc - Books from This Publisher (ISBNs Begin with 978-0-7166)." Books by ISBN - Search Books by ISBN. 2008. Web. 15 Dec. 2010. <http://www.books-by-isbn.com/0-7166/>.

The World Book Encyclopedia. Chicago: World Book, 2000. 217+. Print.

Adnes, Michael. "Sound Waves." Websters Dictionary. Print.