A rare antique hearing aid. The moulded ear pieces fit around the pinnae. They are made from two plates, one tin which rests on skin, the other copper which has fleshed toned colouring (hence ‘Invisible’).
The auditory benefits were attributed to magnetism and the box comes with its own ‘Galvanometer’ (which is actually a simple compass) and does confirm that they are magnetic. Each plate is marked “Audiphone, Bernard Cie, 7 Rue De Londres Paris”. The silk lined box is also engraved as shown and is in good condition.
You can read a French newspaper clipping from Feb 1901 extolling their virtues.