Today in Engineering History: Audiphone Hearing Aid Patented
From: Product Design & Development - 09/23/2015

On this day in history, September 23, 1879, American inventor Richard Rhodes
received a patent for a hearing aid called the Audiphone. The device
consisted of a fan made of a hard rubber material that used the operator's
teeth and jaw bone to conduct sound vibrations and improve hearing.

Read the entire article at:
http://www.pddnet.com/blog/2015/09/today-engineering-history-audiphone-hearing-aid-patented