The Steirische Harmonika (German pronunciation: [ˈʃtaɪ̯rɪʃə harˌmoːnika]) is a type of bisonoric diatonic button accordion important to the alpine folk music of Austria, the Czech Republic, Slovakia, Slovenia, the German state of Bavaria, and the Italian South Tyrol. The Steirische Harmonika is distinguished from other diatonic button accordions by its typically richer bass notes, and by the presence of one key per scale row that has the same tone on both compression and expansion of the bellows, called a Gleichton. The bass notes earn the distinction because they use bigger reeds with duralumin reed frames and a special chamber construction that amplifies its bass tones to give it a loud sound reminiscent of a Helicon tuba.
The name "Steirische Harmonika" literally translates from German as Styrian accordion, but the use of the adjective steirische stems from the Viennese dialect, where it refers to folk music in general. There is no connection to the nearby state of Steiermark, or Styria as it is traditionally called in English, though this type of accordion is in use there as well.
The Steirische Harmonika has melody side on the right, and a bass side on the left. On the melody side, there are three to five rows of buttons where each row has its own key. Accordions with five rows are not much used, but most manufacturers do produce quite a few. On the compression of the bellows, the buttons of one row play the tones from the key's tonic, and on the expansion of the bellows, the buttons of one row play tones from the key's dominant seventh. The button which plays the same tone on both the expansion and compression of the bellows is called the Gleichton, ("same-tone" in German). Often melodies require playing buttons from different rows because they cannot be decomposed into tones from the tonic and dominant seventh of a given key.