Thijs van Leer

Thijs Van Leer (pronounced: ; born 31 March 1948) is a Dutch musician, singer and composer, best known for heading the Dutch progressive rock band, Focus, as primary vocalist, Hammond organ player, and flautist. He also yodels and whistles. In his later years, Van Leer went on to release many solo albums which were also classical music and jazz-based.

source: Wikipedia