Rosen, Hans Waldemar (1904–94), music teacher and choral conductor, was born 15 July 1904 in Dresden, Germany, the only child of Ferdinand Rosetzka and Hedwig Rosetzka (née Thiele). In 1919 his father changed the family name to Rosen. Primarily of German extraction, he was reared in Dresden until his family moved to Görlitz during the first world war. After attending gymnasium in Görlitz, he worked in a local bank before entering Leipzig University in 1925 to study musicology; by age twenty he was conducting a theatre orchestra. Continuing his studies at the university of Innsbruck, Austria, from 1926 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). He also brought the RÉ Singers on numerous trips to continental radio stations and festivals between 1958 and 1972, producing often rebroadcast recordings in all major German radio stations as well as in Holland, Belgium, France and Switzerland.
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 founder and for many years secretary of the Irish branch of the Heinrich Schütz Society, which spearheaded the mid-twentieth-century revival of interest in baroque music; he was also on its international council. 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.