Mickey Mouse
Audiences at the time of "Steamboat Willie"'s release were reportedly impressed by the use of sound for comedic purposes. Sound films or "talkies" were still considered innovative. The first feature-length movie with dialogue sequences, "The Jazz Singer" starring Al Jolson, was released on October 6, 1927. Within a year of its success, most United States movie theaters had installed sound film equipment. Walt Disney apparently intended to take advantage of this new trend and, arguably, managed to succeed. Most other cartoon studios were still producing silent products and so were unable to effectively act as competition to Disney. As a result, Mickey would soon become the most prominent animated character of the time. Walt Disney soon worked on adding sound to both "Plane Crazy" and "The Gallopin' Gaucho" (which had originally been silent releases) and their new release added to Mickey's success and popularity. A fourth Mickey short, "The Barn Dance", was also put into production; however, Mickey does not actually speak until "The Karnival Kid" in 1929 when his first spoken words were "Hot dogs, Hot dogs!" After "Steamboat Willie" was released, Mickey became a close competitor to Felix the Cat, and his popularity would grow as he was continuously featured in sound cartoons. By 1929, Felix would lose popularity among theater audiences, and Pat Sullivan decided to produce all future Felix cartoons in sound as a result. Unfortunately, audiences did not respond well to Felix's transition to sound and by 1930, Felix had faded from the screen.
André Charlin
Charlin became involved in cinematography at a time when sound was starting to be added to motion pictures, and began to build equipment for synchronous sound playback.
At first this used 33 rpm records.
The first "talkies" appeared in 1931, and Charlin began working on ways to improve sound quality through better recording technology.
He founded a recording studio in 1933 that produced the sound tracks for many prewar movies, including in 1934 a stereo sound track for Abel Gance's 1927 silent movie "Napoléon".
He moved into techniques for film projection with a 1935 patent for "Cyclope" focussing and a 1938 patent for "Actua Colour" to project colour films which was used in over 1,000 movie theatres by 1948. 
During World War II he turned to making dynamos to power the lamps of bicycles.
In 1949 Charlin stopped producing cinema equipment and sold all his related patents to Philips of the Netherlands.
Early in the 1950s Radio-Cinema, a subsidiary of the Compagnie générale de la télégraphie sans fil, acquired Charlin' company.