http://www.dansdata.com/images/hd280/hd280_800.jpg
One of the earlier origins of the headphone were used as telephone communicators. Created by Ernest Mercadier in 1891, the headphones were basically tiny and light loudspeakers which were fitted on to the ears. This design later inspired Electrophone system from the U.K. to distribute audio to customers in 1985. The service provided headphone users with audio from live opera, theater and sermons, thus the first form of listening to music through headphones.
http://www.britishtelephones.com/electrophone/electrophone%20users.jpg
The first headphone with the use of amplifiers was created by Nathaniel Baldwin in 1910. By developing amplifiers, he produced more sensitive receivers and therefore better quality headphones. Although the chunky headphones were not popular, it was tested by the U.S. Navy for communication. The headphones proved to be more useful than the Naval radio operators previously used and Baldwin was asked to produce more of these headphones which he gradually did from his kitchen. The headphone design would later be used during WW1 and WW2.
Following World War II and the emergence of Rock n' Roll, John Koss invented the first stereo headphone in 1958. He was fascinated with audio technology and the headphones used at the time, but noticed that the headphones were only made for warplanes and communication instead of music. He therefore created the stereophonic headphone which would became well-known for its transportability and good sound quality. The innovation also became popular for its feeling of being "enclosed in the music".
The design of the first stereophonic headphone would inspire other companies to create their own headphone design. As its technology improve throughout the years, the headphones improved further in quality and transportability. Today, the small white earphones created by Apple have become so popular that it would be hard to walk around a city and not find someone listening to music through these small loudspeakers.
http://www.schubincafe.com/2011/02/11/headphones-history-hysteria/
http://www.britishtelephones.com/electrophone.htm
http://www.koss.com/en/about/history
http://blogs.smithsonianmag.com/design/2013/03/a-partial-history-of-headphones/
http://brompton.com/education/9766
http://www.randomhistory.com/2008/08/20_headphones.html