&gt; 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&#x27;t.<p>There hasn&#x27;t been a major change in the amount of bandwidth or function for headphones.<p>RJ11 was, and still is, a perfectly fine standard if all you need is two or four wires.  But that wasn&#x27;t enough to meet the requirements for hundreds or thousands of megabits of data.<p>The bandwidth of the human ear hasn&#x27;t improved, and over short distances the analog transmission of headphones isn&#x27;t usually a problem.<p>The only thing we&#x27;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.