Nonetheless, Pavel did take out patents in a number of territories. Sony ended up embroiled in several lawsuits regarding patent infringement. Pavel lost at least one, while others were settled by Sony.
So, undoubtedly, Pavel came up with an idea first. But it was Sony that made a commercially viable product, and Sony was the company that took the entrepreneurial risk of releasing the Walkman, even though most seemed to think that no one would want to wear headphones on the street.
And with the Walkman, Sony changed the world, allowing people to listen to their music nearly everywhere.