The Steirische Harmonika is a type of bisonoric diatonic button accordion important to the alpine folk music of Croatia, 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.

Accordions are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type. The essential characteristic of the accordion is to combine in one instrument a melody section, also called the diskant, usually on the right-hand keyboard, with an accompaniment or Basso continuo functionality on the left-hand. The musician normally plays the melody on buttons or keys on the right-hand side, and the accompaniment on bass or pre-set chord buttons on the left-hand side. A person who plays the accordion is called an accordionist.