Lou Koster was born on 7 May 1889 in Luxembourg City into a family of musicians. Her grandfather, Franz Ferdinand Bernard Hoebich, the first military bandmaster, taught her music theory, violin and piano, a privilege that was granted to few girls at that time. Lou Koster completed her studies at the Conservatoire de la Musique, which opened in 1906. She herself taught there from 1908 to 1954.
Her first public appearances were, together with her sisters Laure (Lory) and Lina, musical accompaniments to silent films or occasional concerts. Like her sister Lory Koster, the musician also enjoyed swimming. During breaks between races at the Luxembourg Swimming Club, Lou Koster accompanied the interludes of an orchestra set up above the shower cubicles on the piano.
But her real passion is musical composition inspired by romanticism. She explains: "Just as a painter plays with colours to make a composition that translates feelings and emotions, I compose melodies that can express in music what I feel when I read an evocative poem. The artist has set many works by Alfred de Musset, Paul Verlaine, Nik Welter and Willy Goergen to music. The composer is particularly interested in Luxembourg poetry. Her adaptation of Batty Weber's libretto into an operetta marked the beginning of her career as a composer. Her instrumental compositions for orchestra are less well known.
Although Lou Koster was a shy young woman at the beginning of her career, lacking in self-confidence and plagued by doubts about her professional skills, she became more confident with age and was able to value her works. Nevertheless, Lou Koster remains aware of gender inequality and advocates for women's rights: "Wann ech e Mann wir, dann hätt ech et vill méi einfach".
Lou Koster became particularly famous for his late work based on a text by Nik Welter. The first public performance took place in 1972 in the Echternach basilica, one year before his death. More than thirty years later, two more concerts were organised in September 2009. Then, in order to safeguard Luxembourg's musical heritage, the Centre national de l'audiovisuel recorded the ballad on CD.
Lou Koster died on 17 November 1973 in Luxembourg City. Al Schmitz describes her character in an article in the Tageblatt: "So war auch die Frau, welche diese Musik schrieb. Schlicht und bescheiden, doch kämpferisch, wenn es um die Rechte der Unterdrückten und der Minderheiten ging. Lou Koster trauerte einer fast utopischen Romanik nach, doch wunderte es ihre Freunde nicht, sie in Anti-Kriegs- Meetings oder bei Versammlungen der Frauenbewegungen zu sehen. Lou Koster verabscheute physische Gewalt, viel mehr noch die Unfreiheit des Geistes."
● Danielle Roster: Die Komponistin Lou Koster (1889-1973) in Wenn nun wir Frauen auch das Wort ergeifen pages 290-307.
● Al Schmitz. "Lou Koster 1889-1973. Der großen Luxemburger Komponistin zum Gedenken." In: "Tageblatt", 26. November 1973.
● Press kit "Der Geiger von Echternach": http:www.trifolion.lu