Plugged-In Michelle Pfahles Grade 10 Mrs. Harlan New Castle Sr. High School

Observation Everyday, 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 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 adphones.php

Variables o Independent Variable- Type of Earphones o Dependent Variable- Sound Quality o Controls- Distance of earphones from microphone How long each note is played Audacity program Quiet room where the test takes place

Materials  different types of earphones (Apple, iHip, off-brand earphones, … ect.)  audacity program  microphone  two computers

Procedure 1.Obtain 4 different types of earphones  iHeadphones 4  iHeadphones 5  iHip  Offbrand earphones 2.Download audacity onto both computers 3.Find a quiet and enclosed room with a table 4.Open audacity on both computers 5.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 microphone 9.Save each sound clip with the number of Hz and the earphone brand 10.Change the earphones 11.Repeat steps 8-9 for each set of earphones 12.Analyze and rate the quality for each earphone  1 st = Best Quality= 4 points  2 nd = Good Quality= 3 points  3 rd = Okay Quality= 2 points  4 th = Worst Quality = 1 point

Analyze 100 Hz

Results