In February 1979, Sony co-founder Masaru Ibuka approached engineer Nobutoshi Kihara with a request for a portable device to listen to opera during long flights. Kihara quickly built a prototype, the TPS-L2, by modifying an existing Sony recorder, resulting in a lightweight device designed for headphone use. Launched on July 1, 1979, in Japan for ¥33,000 (about $300 USD), the Walkman faced skepticism from Sony's marketing team, who doubted the viability of a non-recording cassette player. Despite this, the Walkman exceeded initial sales expectations, selling 30,000 units in just two months. Its design, which included two headphone jacks, was aimed at encouraging shared listening, though it ultimately popularized solitary music experiences. The Walkman revolutionized how people consumed music in public, leading to the term 'Walkman effect' to describe the personal acoustic space it created. By 1986, the name had entered the Oxford English Dictionary, signifying its cultural significance. Over the next decade, Sony sold 50 million units, paving the way for future portable music devices like the Discman and iPod.