The violin is the soprano member of the family of the bow chordophones, which include the viola and the cello. The instrument has a great sustained sound capacity and a great spectrum of expression and intensity. Its sonority is usually obtained by the smooth sliding of the bow over the strings; the vibrations are transmitted through the bridge to the soundboard, and through the soul to the bottom. The four strings violin, already known in 1550, was preceded by a three strings violin. The latter was a cross between the rebec, the Renaissance rabeca and the lira de braccio (developed form of rabeca). At the dawn of the 16th century, the Italian school of violin makers appeared (Andrea Amati in Cremona, Gasparo de Saló in Brescia), making adaptations and improvements in the instrument. These modifications were important so that the structure would enable musicians to play the works of composers of the 17th century, who were more demanding, particularly regarding operas, sonatas and concerts. In the 19th century, orchestras and concert rooms required more of the sound potential of the instrument, and the luthiers from this period improved manufacturing techniques even more. In 1800, the shape and technique of violins had already been standardized, despite the fact that the chinrest was invented and added around 1820, by Spohr. However, this was considered a modification of minor importance. Nowadays, the violin still goes through some adaptations: internal reinforcement, higher elevated bridge, neck in a sharper angle in relation to the body (to allow more tension on the strings), longer fingerboard (to reach higher notes). The present repertoire for violins is large: sonatas, chamber music, concerts, light music, pieces seeking to show a high technical level, among others. Besides, like other bow chordophones, the violin now can be electronically amplified, and in this case, it has a hollow structure of different shapes.
