She composed for a large variety of instruments, yet is particularly active in composition for voice. These works extend from solo vocalists to choir music. Many of her compositions for voice set poetry to music. To this end she has utilized texts by Gerrit Achterberg, Anna Bijns, Emily Dickinson, Wiel Kusters and Elly de Waard, among others. She is also an accomplished and decorated poet herself.
Ehlen studied composition with Gerard Kockelmans, Willem de Vries Robbé and Robert Heppener, piano with Bart Berman and Kees Steinroth and choir conducting with Jan Eelkema. She graduated with a degree in music education from the Conservatoire of Maastricht, and taught at teacher colleges in Rotterdam, Maastricht and Sittard. She has collected and analyzed the works of her fomer teacher, the Dutch composer Gerard Kockelmans.
Many of her works were published by Donemus, a not-for-profit Dutch publishing house that promotes contemporary classical composers. Some others were published by the Rieks Sodenkamp publishing house in Maastricht.