Rosen, Hans Waldemar (1904–94), music teacher and choral conductor, was born 15 July 1904 in the then German region of Silesia, the only child of Ferdinand Rosen and Hedwig Rosen (née Thiele). Of mixed German and northern Slav extraction, he was reared in Breslau (latterly the Polish city of Wroclaw). After attending gymnasium in Görlitz, he studied in Leipzig at both the state conservatory and the university, and by age 20 was conducting a theatre orchestra. Continuing his studies at the university of Innsbruck, Austria, he directed the university choir and received a D.Phil. in musicology (1930). During the 1930s he established himself as a music critic in Leipzig, becoming in 1936 programme editor with the Gewandhaus Orchestra and editor of a music magazine. He wrote a biography (1935) of Johann Sebastian Bach, and published many musicological articles. Conscripted into the German army in 1939, he served as a war correspondent till his capture by the British and internment as a prisoner of war in Wales.
Moving to Dublin in 1948, he lived for some time in the Salvation Army hostel on York St. before setting up as a physiological voice teacher. With a studio in the Four Provinces House, Harcourt St. – headquarters of the bakers’ trade union, whose secretary, John Swift (qv), was developing the venue as a broad cultural centre – he rapidly established a reputation as an instructor of impeccable vocal technique as well as musicianship, his many distinguished students including Frank Patterson (qv), Veronica Dunne, and newsreader Charles Mitchel (qv). Rosen was one of many musicians from central and eastern Europe, either refugees or recruited by Radio Éireann (RÉ) from their homelands, who played an important part in enriching Ireland's musical environment at a time when there was a dearth of native players and teachers. Joining RÉ in 1950, he conducted the RÉ men's vocal octet, and was among several conductors of the station choir, Cór Radio Éireann. When these bodies were supplanted by two new combinations, Rosen became director of the amateur Radio Éireann Choral Society (founded 1952), and conductor of the professional Radio Éireann Singers (1953), a chamber choir of four male and six female voices. Drawing on his own exceptionally wide musical knowledge, he trained both bodies in a broad and eclectic repertoire, ranging from Handel and Schumann to Stravinsky and Hindemith, and premiering works by such Irish composers as Brian Boydell (qv) and Gerard Victory (qv). Exercising a lengthy and defining influence over RÉ's substantial output of live and broadcast vocal music, he thereby played a major role in the development of music in Ireland generally. Keenly interested in music education, he brought the RÉ Singers to the seminars in contemporary choral music at UCC under Professor Aloys Fleischmann (qv).
A sometime conductor of the RÉ Symphony Orchestra, in 1965 he was appointed vocal director of what had become Radio Telefís Éireann. He frequently conducted the choir of Dublin's Goethe Institute, and was Irish branch secretary and international council member of the Heinrich Schütz Society, which spearheaded the mid-twentieth-century revival of interest in baroque music. A guest conductor with the BBC, London, and the Dutch broadcasting service, NVCR, Hilversum, he belonged to numerous Irish and continental European music societies, and was a Knight of the White Rose of Finland and an Officiale d'Italia. Long resident in Dublin at 55 Strand Rd, Sandymount, on retirement from RTÉ he moved to Sneem, Co. Kerry, where he formed a local choir and commuted to conduct the Limerick Choral Union. A large, affable man, who exuded enthusiasm for all his myriad interests, Rosen was possessed of a vibrant and infectious zeal for music in all its genres. He married (1939) Eva Trint (d. 1963); they had one daughter and two sons, the youngest of whom was born in Ireland. He died 3 April 1994 in the Ailesbury nursing home, Sandymount; after a memorial service in St Finian's Lutheran church, Adelaide Rd, he was interred in Cruagh cemetery, Rockbrook, Rathfarnham.