Do small aircraft have sockets for passenger headsets? I am currently training for my PPL. in the Cessna 182s we use I've only ever noticed two sets of ports for the headsets. If there were additional passengers in the back seats, how would they communicate?
The rear seats of a Cessna 172 has headset jacks, I imagine the 182 has the same.

You can see them in this picture:



Image source

You might also find them over the shoulder of rear passengers - as can be seen in this image (copyright attached)


That links the rear-seat passengers to the same intercom you're used to from a front seat passenger.