Starting in the latter half of the 20th century, people have been able to own devices that allows them to be mobile and listen to audio, particularly music. Since then, the sophistication and variety of such devices has evolved considerably.
In 1954, Regency Electronics Inc. introduced a pocket transistor radio called the TR-1. Priced at $49.95, it was the first portable audio device made for commercial purchase. With the invention of the TR-1, people no longer needed to sit at home to listen to the radio.
In 1979, Sony took portable audio a step further by introducing the Walkman, the first portable music player. It was powered by two AA batteries, had a phone jack to plug in earphones, and used the music storage of the age--the eight-track tape.
Cassette and Continued Sony Dominance
By the 1980s, the cassette tape had phased out the eight-track as a less bulky, more efficient music source. Its size was no bigger than a deck of cards, and it was able to move faster from one track to the next. By this time, Sony no longer held monopoly over the market. Other manufacturers, such as like Aiwa, Sanyo, Sharp, Toshiba, and Panasonic, fiercely competed with Sony. Some even offered additional features (such as the ability to play radio as well) or better portability with their audio players. Nevertheless, portable audio remained eponymous with Sony's Walkman throughout the 1980s.
Compact Disc Technology
By the early 1990s, the compact disc had replaced the cassette tape as the dominant music source for portable audio players, and the portable CD player entered the market. Unlike the previous technology, which requires one to rewind or fast-forward to get to a track, one can press a button on the CD player to skip to the previous or next track on the CD. Also, CDs were not prone to the tape damage that cassette were subject to over time.
However, CDs were subject to something else: scratches on its playing surface, adversely affecting audio playback. As for CD players, they tended to be bulkier than cassette players and, at least until the invention of anti-skip technology, skipped when the laser light reading devices on them were shaken to a certain degree, thus making it a less-than-ideal device for sports enthusiasts.
The Digital Age
MP3, a digital audio encoding, grew in use toward the end of the 1990s, and the format dominates today's portable audio market. With computer memory stored in them, not only do MP3 players eschew the use of removable music storage altogether for audio playback, they have the capability of storing more music. They also tend to be a lot smaller and they do not skip. Although several makes and models of MP3 players exist today, the iPod, manufactured by Apple, is by far the most popular one. With the iPod and the other MP3 players on the market, one can play video games, surf the Web, take pictures and watch movies.