Johann Christoph Denner is the man that is credited with inventing and building the clarinet. His son, Jacob is also credited for helping him. The idea of a clarinet wasn't a brand new one at the time. It was actually an improved idea of the chalumeau. The chalumeau was the first instrument to use a reed; Denner took that instrument and gave it a couple extra keys.
He also enabled the instrument to play an extra two (or more) octaves. Though Denner is given credit for turning the chalumeau into the clarinet, there is actually no documented proof—two of Denner's contemporaries also built clarinets as well.
Johann Christopher Denner has been credited to be the inventor of clarinet. Johann Christopher is a renowned German musician and performer. He was born in Leipzig, Germany on the 13th of August 1655. He lived in Nuremberg where he also died on the 20th of April 1707.
Around late 17th century and early 18th century, Johann and his son Jacob, worked on a musical instrument called chalumeau, they improved the chalumeau to form another instruments called the Clarinet. Johann is also known to be one of the people that refined many woodwind instruments. He learnt how to build instruments from his father who made horns to call animals. After Johann's death, his son continued to improve the clarinet.