Ferdinand Sieber was a Viennese, Italian-trained voice teacher who knew the importance of vowel alteration and its role in keeping the balance of the registers. The Sieber Vocalises are designed to balance the registers using 8-measure melodies based on the Italian syllables da, me, ni, po, to, la, be. The register balance is achieved in the way Sieber arranges the syllables. His goal was to allow the space of the open vowels in the closed vowels, and the ring of the closed vowels in the open vowels. These vocalises can be described as the 'bridge between vocalizing and singing music'. Sieber wrote a different group ofexercises for each voice type (i.e., tenor, bass, baritone and soprano, mezzo, and alto).