The Steirische Harmonika (German pronunciation: [ˈʃtaɪ̯rɪʃə harˌmoːnika]) is a type of bisonoric diatonic button accordion important to the alpine folk music of Slovenia, the Czech Republic, Austria, 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 Helikonbässe 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.