The Viola Beiroa is a stringed musical instrument from Castelo Branco, Eastern Portugal. It has 12 strings in 7 courses. The strings are made of steel. It is tuned D3, D3, A3 A2, D3 D2, G3 G2, B3 B3, D3 D3. The scale length is about 520mm. A string instrument (or stringed instrument) is a musical instrument that produces sound by means of vibrating strings. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones. The most common string instruments in the string family are guitar, electric bass, violin, viola, cello, double bass, banjo, mandolin, ukulele, and harp.