> How is that even possible? RJ11 phone jacks I think were introduced around the same time, but they seem archaic and old-fashioned in a way the 3.5mm audio jac

> How is that even possible? RJ11 phone jacks I think were introduced around the same time, but they seem archaic and old-fashioned in a way the 3.5mm audio jack doesn't. There hasn't been a major change in the amount of bandwidth or function for headphones. RJ11 was, and still is, a perfectly fine standard if all you need is two or four wires. But that wasn't enough to meet the requirements for hundreds or thousands of megabits of data. The bandwidth of the human ear hasn't improved, and over short distances the analog transmission of headphones isn't usually a problem. The only thing we've added to headphones in the recent years are a limited number of playback control buttons and a microphone, which have evolved the port only a little bit.