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over-the-head headphones often use passive noise canceling instead of active

You are required this week to write an essay concerning the physics of Sound. Sound Discussion Using the How Stuff https://science.howstuffworks.com/sound-info.htm website, your text, and any other information, choose one item that uses sound technology. (ie. HDTV, iPod, cell phone, etc.) and write an essay on how the item works. Continue the essay to explain how the item you chose demonstrates the physics of sound. It must be detailed and uses Physics terms. Everyone will be posting their essay in the Discussion section of Canvas.

Each person must pick a different sound item. In other words, one item per student. Whoever lists the item first will receive credit. Make sure you do not write your essay on an item that someone else has already used. Student response: You are also required to respond to ONE students’ essay. Please comment scientifically about your fellow classmates’ essay. Use physics terms, instead of “nice essay, I liked it…” ONE FULL PAGE IS FOR THE ASSIGMENT AND THE HALF IS FOR THE RESPONSE. Here is the student’s essay; I am choosing active noise-canceling earbuds. Noise-canceling earbuds block out ambient sound from entering your ear, but I have always wondered how they do this. It turns out the earbuds have a microphone and speaker inside of them that listen to the ambient noise around you and match that frequency and then play that same sound wave back but does it 180 degrees out of phase which effectively cancels the sound and makes it silent to your ear. Just like we learned about wave interference, the headphones match the crest of the sound wave with an equal trough which creates an area of zero amplitude

. This is destructive interference. To do this the earbuds must have a battery source to power the speaker that plays the music or whatever you intend to listen to, and it must also power a much smaller speaker and microphone that listens to and cancels out the ambient noise. This is why when you use active noise canceling, your battery dies much quicker on your headphones. As an important side note, over-the-head headphones often use passive noise canceling instead of active, which is just the thick padded material that blocks the sound from getting to your ear. These often have much longer battery life for that reason (and obviously because they are larger and can support a larger battery).