Anyone ever seen these before? I’m guessing circa early 70s, I suppose the frequency response is entirely dependent on your wall material 
. Brand new in box! I can find absolutely no info on these. Part of me wants to try them - perhaps I’ll hook 'em up and just hold them to a wall and bask in audiophile bliss. (They are 4" diameter)
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I am reminded of the “bone phones” that would be advertised in the back pages of some magazines.
I’d go ahead and give them a go on some drywall using a cheap AVR if you have one laying around. For optimal performance, but sure to use a stud finder and place them centered between the studs. 
RE: Bone Phones, I bought a pair as a youngster (quite costly as I recall; $70?) and they sucked! Returned for a full refund. They were the blue wrap around your neck style shown below (roller-skate girl not included).
But, the worked, from what I read, to let deaf people hear.