Audience: Middle and High School Students
By: Nina Timofeyeva
Listening to music through headphones is a much more complicated and intriguing process than many know it to be. It is the conversion of a digital file into a physical action and then into sound waves we can hear and interpret.
Everything starts off with your phone or device where the sound you are listening to, also known as an MP3 file, is “written” in binary code. Binary means “two,” so binary code is code that is made up of various patterns of 1s and 0s.
Once you press “play,” your phone sends the code of 1s and 0s to a digital analog converter—or a DAC—which turns the code into electrical impulses. These impulses then travel through the headphone wire from the DAC to the actual headphones.
Inside of each ear cup, there are two magnets—one that is moving and one that remains stationary. The one that moves is an electromagnet. Electromagnets can change their polarities depending on whether electricity is being applied to them or not.
The electrical impulses that were sent to the headphones then go to the electromagnet, which is either repelled or attracted to the stationary magnet due to the electromagnet changing its polarity. Polarity explains whether a magnet is negatively or positively charged, which can be used to predict what type of magnet it will be attracted to. The electromagnet is also attached to a thin membrane (a thin pliable sheet of material forming a barrier or lining), called a diaphragm. When the magnet vibrates, so does the diaphragm. The diaphragm’s vibrations cause air around it to vibrate as well, creating sound waves. These sound waves are then received by our ears and comprehended as music, a podcast, or whatever you are listening to!
Bluetooth headphones work almost exactly the same, except the written code of music consisting of 1s and 0s is not sent to a DAC in your phone, but rather to one that is built into the headphones.
Apple’s Airpods are one of the newest innovations in Bluetooth and headphone technology. Photo from Unsplash by Stehen Phillips
A Timeline: Evolution of the Headphones
1890 - Everything started with phone operators. Operators used a single earpiece that rested on the user’s shoulder and weighed over 10 pounds!
1910 - Engineer Nathaniel Baldwin invented the first pair of audio headphones in 1910. The Navy ordered 100 pairs, not knowing that Baldwin was making them by hand.
1958 - Early models were just mini-speakers covered in cardboard and sofa foam. Instead of creating technology for radio communication and aviation, Koss - an entrepreneur, innovator and creator - came up with headphones used purely for music. This allowed average consumers to partake in the use of headphone technology!
1979 - Sony made headphones portable for the first time with their cassette player, the Walkman, which sold over 400 million units.
2001 - iPods created by Apple Inc. pushed the music industry forward by allowing listeners to enjoy their music on the go.
2004 - Bluetooth headphones are invented and hit the market.
2008 - Headphones became more than just devices—they became fashion statements. Companies like Beats, SkullCandy, Bose, and others started focusing on the appearance of headphones and famous artists wore brands as advertisements.
An example of headphones created to be aesthetically interesting, not purely purposeful. Image from Unsplash by Blaz Erzetic.
Bibliography
I Tech It Easy, Team Itechiteasy - "Here Is How Headphones Work On The Go!" - August 17, 2000
headphonereview, Christian De Looper - "How Do Headphones Work? A Guide to the Inner Workings of Our Headphones." - September 30, 2016
LSTN Sound Co., lstnsound.com - "A Brief History of Headphones" - October 6, 2020
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