Invention of the telephone
The carbon microphone was independently developed around 1878 by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention.
History of hearing aids
The first firm to begin commercial production of the ear trumpet was established by Frederick C. Rein in London in 1800. As well as producing ear trumpets, Rein also sold hearing fans, and speaking tubes. These instruments helped amplify sounds, while still being portable. However, these devices were generally bulky and had to be physically supported from below. Later, smaller, hand-held ear trumpets and cones were used as hearing aids.
Rein was commissioned to design a special acoustic chair for the ailing King of Portugal, John VI of Portugal in 1819. The throne was designed with ornately carved arms that looked like the open mouths of lions. These holes acted as the receiving area for the acoustics, which were transmitted to the back of the throne via a speaking tube, and into the king's ear.
Finally in the late 1800s, the acoustic horn, which was a tube that had two ends, a cone that captured sound, and was eventually made to fit in the ear.