Definitely an old speaking tube. If your house is two stories tall it would have most likely came out by the front door so if a visitor came by and no one answered a knock they could pull the flap up and blow into it and it would whistle to hopefully get some ones attention. Then drop the flaps and be able to talk to each other with out having to go down stair.My parents old house (it was built in 1906) had one. They had silicone filled the hole by the front door. But it was repaired and made to work great.