Audiphone

Audiphone is the name of an invention (1879) by Mr Rhodes of Chicago, to assist the hearing of deaf persons in whom the auditory nerve is not entirely destroyed. The instrument is made of a thin sheet of ebonite rubber or hard vulcanite. It is about the size of a palm-leaf fan, with a handle and strings attached to bend it into a curving form, and a small clamp for fixing the string at the handles. The audiphone is pressed by the deaf person using it against his upper front teeth, with the convex side outwards; when so placed it communicates the vibrations caused by musical sounds or articulate speech to the teeth and bones of the skull, and thence to the organs of hearing. For different sounds, it requires to be focused to different degrees of convexity. A simple strip of fine glazed millboard has been recommended by some experimenters as a cheaper and equally serviceable audiphone; and birch-wood veneer has been used with success for the same purpose.