Ivan Müller, sometimes spelled Iwan Mueller was a clarinetist, composer and inventor who at the beginning of the 19th century was responsible for a major step forward in the development of the clarinet, the air-tight pad. Müller was born in Reval (present-day Tallinn), at that time a city with a strong Baltic German community in the Governorate of Estonia, part of the Russian Empire. He became a chamber musician in Saint Petersburg before he was twenty. At the same time, he was constantly striving to improve the clarinet, with new types of keywork. At the time, the standard clarinet used flat brass plates covered in soft leather to cover the toneholes. Since these leaked air, the number of them had to be kept to a minimum, which meant that notes outside of the main scale of the clarinet (accidentals) had to be obtained by complicated fingerings which were difficult to play quickly and rarely were in tune. Clarinets would have five or six keys, the bare minimum to obtain an acceptable chromatic scale. Müller's solution was the stuffed pad, originally made of kid leather stuffed with felt. These pads would "bulge", such that in combination with countersunk tone holes, would close the keyholes sufficiently tight to permit the use of an increased number of keys making the "clarinette omnitonique" possible.