Carlos Vega 

May 31, 2018

Headphones are a outstanding feat of mechanical engineering and electrical as it shows the clever ingenuity of engineers to solve a problem or simply improve the quality of life. As common as headphones are they are very complex machinery which many people take for granted by their ease of use. Both the audio jack and the main wire are part of the applications of electrical engineering. These parts are essential as the power source to the headphones, as well as controlling the specific currents transferred from the device to the speakers. The speakers are where mechanical engineering truly shines. Cone-shaped films are vibrated at very specific frequencies, determined by the amount of current flowing through the wires of the headphones. These currents are later transferred into an electromagnet within the whole headphone that transmits electromagnetic waves, which ultimately vibrate the speakers. 

Electrical Engineering: 

1. The headphones are powered by the audio jack that is connected to x device. In most instances, the audio jack has 2 groves which are metal discs which are used in order for the signal to be sent to each speaker. These rings on the plug are crucial as it sections of the current to each speaker, it being right and left.[1].  
2. According to WIRED, “At the most basic level, an earphone is a loop of wire with current running through it” [1]. Each speaker has its own circuit so that there can be independent currents for both headphones. Each phone needs at least two wires connecting it to the power source to complete the circuit. The current is sent from the device to the speaker, and then sent back from the speaker to the device after being processed by the speaker.  
3. The device adjusts the current with the programming designed in order for the vibrations of the film to make out audio which is recognizable by our brains. Chris Woodford does an excellent job of explaining this when saying “Banging a drum skin really hard makes the skin vibrate a greater distance and produce a louder sound. In the same way, sending a bigger pulse of electricity into a loudspeaker makes the cone move further and generates a louder noise. Quieter sounds are made by smaller pulses of electricity” [2]. The idea is that this object is able to project from a hearing standpoint a what appears to be limitless amounts of songs, videos or anything else due to the range of vibrations which are converted to mechanical waves. 

Electromagnetic waves  

1. The wire works as a medium for the current to pass through, in essence a electromagnet is then created by sending electric waves through a metal as the current flows it creates magnetic fields which move the mechanism and the films to create waves which are presided as sound. [3]. Having control of the current is very important as it allows to adjust the sound being produced from the diaphragm in the headphones. 
2. The strength of the current determines the strength of the magnet inside the speaker. Another example of this very clever application of mechanical engineering is the magnets which are used to move wreckage in landfills. [3]. The headphones are a great example of the magnetic field’s precision. Changing the velocity of oscillation of the film within the current affects the frequency of charges affecting the electromagnet [4]. This is what gives headphones the ability to play from a spectrum of sounds like rock, hip-hop, EDM According to Schultz Innovation, “The usual frequency range of headphones, at least as it is declared on the packaging of headphones, includes frequencies from 20 Hz to 20,000 Hz, which is what an average human can hear” [5].  

Mechanics

1. The electromagnet underneath the diaphragm is attached to a coil made of metal, acting as the channel between the diaphragm and the magnet [2]. The electromagnetic fields make the system oscillate at incredible speeds, resulting in vibrations in the air within the cone of the diaphragm.  
2. The diaphragm is a piece of paper shapped as a cone that acts as a surface for the waves to be formed as it moves.[2]. These vibrations finally create compression waves in the surrounding air.  
3. This is what creates for us “sound”, it is the unison work of the whole system that creates the final product of vibration which our brains are able to perceive as sound.the “sound” that we all hear when blasting music in our ears. 

This marvel of engineering, which is basically made of two complete circuits that are connected to two cones has become one of the most useful and widely spread products of this age. Dissecting the product gives us an inside on the logistics that goes into the engineering design.  A pair of headphones may not necessarily have to be visually appealing, but what makes them appealing is the complexity of the system with such an ease of use. 

Reference List

[1] R.Allain. (2016). The physics of how your earphone jack works (Just in time to say goodbye). Wired [Online]. Available: https://www.wired.com/2016/09/physics-earphone-jack-works-just-time-say-goodbye/.  

[2] C.Woodford. (2018). Loudspeakers, Explainthatstuff.com [Online]. Available: https://www.explainthatstuff.com/loudspeakers.html. 

[3] M.Brain and L.Looper. (2000). How electromagnets work, Howstuffworks.com [Online]. Available: https://science.howstuffworks.com/electromagnet.htm.  

Available: https://sciencing.com/why-does-magnet-attract-iron-4572511.html.  

[4] Fluke. (2018). What is frequency? [Online]. Available: https://www.fluke.com/en-in/learn/best-practices/measurement-basics/electricity/what-is-frequency. 

[5] Schultz. (2017). Frequency range of headphones explained, schultzinnovation.com [Online]. Available: http://schultzinnovation.com/frequency-range-of-headphones-explained/.