Yodeling is a form of singing that involves singing an extended note which rapidly and repeatedly changes in pitch from the vocal chest register (or "chest voice") to the head register (or "head voice"), making a high-low-high-low sound. This vocal technique is found in many cultures throughout the world.
In Swiss folk music, it was probably developed in the Swiss Alps as a method of communication between mountain peaks, and it later became a part of the traditional music of the region. Yodelling can be split up in two main forms: In Alpine regions, natural yodelling without words can be heard. On the other hand, the so called yodel song combines traditional one voice or choir songs with yodel refrains. On special occasions or as an attraction for tourists the polyphonic yodelling is accompanied by bell-shaking or coin-rolling.