Plugged-In

Michelle PfahlesGrade 10

Mrs. HarlanNew Castle Sr. High

School

ObservationEveryday, I listen to music on

my iPod. I’m always “plugged-in.” One day, I forgot my earphones, so I ran into the store to buy new ones. I got the cheapest pair of earphones that they had. When I plugged the new earphones into my iPod, I realized that it sounded much different than when I used my other earphones. This lead my to wonder if certain brands of earphones affected the quality of the music we hear. I wondered if certain earphones would produce better sound quality in high range, low range, and middle range.

Research~frequency- number of complete

cycles per second~Hertz (Hz)- unit of frequency in a

cycle of a sound wave~20 Hz is the lower limit of human

hearing~22000 Hz is the upper limit of

human hearing~oscilloscope- instrument used to

analyze and display waveform~waveform- represents the

alternating current changes with time (sine, square, ramp, saw tooth, and triangular)

~Audacity is a program used to produce or record Hz or any other audio

Sources "Audacity: About Audacity."

Audacity: Free Audio Editor and Recorder. N.p., n.d. Web. 25 Nov. 2013. audactiy.sourceforge.net/about

"The Ultimate Headphones Test." Audio Tests, Test Tones and Tone Generators - Online and Free. N.p., n.d. Web. 25 Nov. 2013. www.audiocheck.net/soundtests_headphones.php

Variableso Independent Variable- Type of

Earphoneso Dependent Variable- Sound

Qualityo Controls-

Distance of earphones from microphone

How long each note is playedAudacity programQuiet room where the test takes

place

Materials different types of earphones

(Apple, iHip, off-brand earphones, … ect.)

audacity program microphone two computers

Procedure1. Obtain 4 different types of earphones

iHeadphones 4 iHeadphones 5 iHip Offbrand earphones

2. Download audacity onto both computers3. Find a quiet and enclosed room with a table4. Open audacity on both computers5. Create a file on audacity. Play each sound for a

total of five sections, and leave one second of rest time in between each sound

– 100 Hz– 200 Hz– 400 Hz– 800 Hz– 1600 Hz– 3200 Hz– 6400 Hz– 12800 Hz– 22000 Hz

6. Plug microphone into the computer with the file and place other side into the hole drilled in the Styrofoam

7. Plug earphones into the other computer and place an earbud into the opposite hole in the Styrofoam

Procedure cont.8. Record the file produced on the computer with the

microphone9. Save each sound clip with the number of Hz and

the earphone brand10. Change the earphones11. Repeat steps 8-9 for each set of earphones12. Analyze and rate the quality for each earphone

1st = Best Quality= 4 points 2nd = Good Quality= 3 points 3rd = Okay Quality= 2 points 4th = Worst Quality = 1 point

Analyze100 Hz

0 5000 10000 15000 20000 25000

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

iHeadphones 4

0 5000 10000 15000 20000 25000

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

OffBrand

0 5000 10000 15000 20000 25000

-70

-60

-50

-40

-30

-20

-10

0

10

20

iHip

0 5000 10000 15000 20000 25000

-60

-50

-40

-30

-20

-10

0

10

20

Iheadphones 5

Results