Pretty surprising to hear there's air/sound tubes rigged on to every seat on a plane.
Seems like the sound tubes ended in the 70's: https://apex.aero/articles/sound-tube-surprising-history-air...
Either because they didn’t want you to take their headphones from the plane, or so they could charge for use because you couldn’t just plug in your Walkman headphones.
Or both.
Either on the headphones themselves or in the little overwrap bag there was a note to leave them on the aircraft when you deplane, because they (obviously) wouldn’t work elsewhere.
I was still encountering them in the early '90s, although by that time they had become uncommon.
I'm 40-ish, and I remember them as a child, so they were definitely still kicking around in the mid to late 80s, most likely on KLM and Pan Am, that were the airlines of my childhood.
https://avidproducts.com/2023/12/08/celebrating-70-years-of-...
apparently the speaker was in the armrest.