This folder contains correspondence relating to Edison's work on a hearing aid. Following the appearance in early 1878 of articles about the phonograph, which drew attention to his own deafness, Edison began receiving inquiries about his proposed invention of a hearing aid. In 1879 many of these correspondents again wrote to Edison to inquire about the current state of the invention. There were also some original inquiries about the device.

Less than one percent of the documents have been selected. These items received significant replies or were written by individuals associated with Edison.