Have you noticed, in the recent times, how the number of people with musical devices (walkmans, discmans, mp3 players) have increased?
Some years ago, when I was little, the media most used was the LP(Gramophone Record). It was big, and required a reproduction device that was even bigger than the LP itself. It wasn’s portable. Then, it came Walkmans, I don’t know when they came, but when I was little, you could saw a few people with one of those, hearing a radio or a Cassete Tape. But if you wish to hear your preferred music, you had to record manually a Cassete Tape, which took just too many time. I think for this reason the walkman never was a fever, but it got popular.
Some years later came the CD, and I don’t know how much time later, but the Discman came along, and people could take CDs everywhere, and listen to them. The Discman became popular, and became even more popular as the CD-Writers got populars too. You could copy your favorite music on a CD, and then play it on your Discman, and it took little time, compared to Cassete.
With the appearance of MP3, some discman got the feature of playing mp3 CDs, which contributed to the popularization of the “Portable Music Devices”. When the Mp3 players started to appear, they were very expensive, but they did what the most people wanted at the time: To get their favorite musics with them, in a Re-Recordable media, which was fast to load.
And I think this is the reason that nowadays is getting more and more common to see people with a headphone on the streets. And the Mp3 Players are getting more popular everyday.