Bb Soprano Trombone, also referred to as a slide trumpet. http://www.youtube.com/watch?v=DKlvqbBWy3Y
According to the Smithsonian: This trumpet was made by Getzen Company, Inc. in Elkhorn, Wisconsin in 1963. It is a B-flat slide trumpet made of brass and nickel plate. This instrument is really a soprano trombone but sold as a slide trumpet by the manufacturer.
ALTA CAPPELLA An alta cappella or alta musica (Italian), alta musique (French) or just alta was a kind of town WIND BAND found throughout continental Europe from the thirteenth to the eighteenth centuries, which typically consisted of SHAWMS and SLIDE TRUMPETS or SACKBUTS. WAITS were the British equivalent. These were not found anywhere outside of Europe. Alta musique in general refers to the "loud music" of instruments like shawms, sackbuts, trumpets, and drums, in contrast to basse…
"En wyflicht beildt ghestadt", an anonymous piece from the 14th century, most probably in Dutch, performed by the Ensemble Servir Antico [Trio medieval]: Catalina Vicens (organetto), Baptiste Romain (vielle) and Félix Stricker (slide trumpet). See www.ensembleservirantico.com, www.catalinavicens.com, www.baptisteromain.com