This sounds a whole lot like the Baird "Phonovision" process which used aluminum discs in the 30's. It is a recording of the modulated pulse that comprised the mechanical signal for the video portion of the transmission. You can see Don McLean's efforts in England on his restoration of the same type of discs discovered there on his website. Great history here.
This could be the only known recording of mechanical televison in the states. A real find for whomever knew it. I suspect it is the video and not the audio portion of the program. Acetate would have been used for the audio unless this is a master pressing for later use.
I think you need a fiber needle for these. If it is audio you will know. If it sounds like a modem, it is video.
http://www.tvdawn.com/silvaton.HTM
Dave A