Musical reproduction technology was made portable by Sony, which rolled out the first Walkman in 1980. The first Walkman was essentially a radio; later it was modified to play cassette tapes and compact discs. Towards the end of the 1990s, a new technology came out called DAT, but it quickly flamed out. Now, of course, there are iPods and Smartphones, and you use ear buds to listen to them; the early Walkmans had headphones.
I can't close without mentioning the headphones you find in the airliners. These days, they're padded like real headphones and they attach with universal jacks, but when stereo sound was first introduced on aircraft, the early headsets looked like today's earbuds, only they were attached to hard plastic stalks as opposed to dainty hairstrand-like wires. I still have permanent creases in my inner earlobe from listening to those cross-country. And a permanent dislike for anything by Olivia Newton-John.