Walkman is a Sony brand tradename originally used for portable audio cassette players, and now used to market Sony's portable audio and video players as well as a line of former Sony Ericsson mobile phones. The original Walkman introduced a change in music listening habits by allowing people to carry music with them and listen to music through lightweight headphones. The prototype was built in 1978 by audio-division engineer Nobutoshi Kihara for Sony co-founder Masaru Ibuka, who wanted to be able to listen to operas during his frequent trans-Pacific plane trips. The original Walkman was marketed in 1979 as the Walkman in Japan and, from 1980, the Soundabout in many other countries including the US, Freestyle in Sweden and the Stowaway in the UK. Advertising, despite all the foreign languages, still attracted thousands of buyers in the US specifically. Sony President and co-founder Akio Morita hated the name "Walkman" and asked that it be changed, but relented after being told by junior executives that a promotion campaign had already begun using the brand name and that it would be too expensive to change.