The personal stereo is the term given to a portable audio player using an audiocassette player. This allows the listening of music through headphones while a person is mobile. The first personal stereo was the Stereobelt invented and patented by Andreas Pavel in 1977. Pavel attempted to commercialise this invention but failed to do so. The first commercial personal stereo was the Sony Walkman released in 1979, created by Akio Morita, Masaru Ibuka (the co-founders of Sony) and Kozo Ohsone.
The Walkman was a popular product and brand for Sony, making a lot of money for the company. The personal stereo concept was quickly cloned by other manufacturers and became the most widely used method of listening to music while travelling or exercising. This lasted, in more technological advanced countries, until the advent of other types of portable audio players such as the Minidisc and MP3 players. In some countries where more modern technology is not available or affordable, the audiocassette and personal stereo are still seen in everyday life.
Whilst the Walkman itself was a brand originally used for the Sony personal stereo players, it is now used by Sony itself for different forms of portable audio devices.