On Friday, April 3, 2015 at 9:23:59 PM UTC-7, 2phar wrote:

There are seven of these sockets within a 1964 built house in Michigan USA:

"http://i60.tinypic.com/2628481.jpg"

That's a two-pin Jones plug. General purpose connectors, not approved for
household AC power, nor intended for RF. So, speaker wiring seems likely.