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.
Mārtiņš Saulespurēns
Saulespurēns and Wise also built microphones to handle digital processing (extended frequency response, dynamic range, etc.). They used a movable round brass plate instead of a permanent membrane in the rear part of the capsule. This allowed Blue to move the plate to change the volume of the air inside, changing the frequency response. The first microphone they created was the Blueberry. The replacement of rear Mylar film membranes with solid tuned brass pieces became standard industry practice.