One of the first female composers

Kassia [in Gk. Κασσιανή] was a Byzantine composer [living from 805 A.D. - 865] who is widely regarded as the first famous female music scorer. She was an abbess and a poet, and composed hymns that are still used in the Orthodox Church's liturgy books. Listen to her work here. And try one of her hymns sung by the Boston Byzantine Choir here.

Also try Cappella Romana's album 'The Fall of Constantinople'. If you want to hear the Orthodox Church's sung liturgy in English, it's very interesting and odd to hear it instead of read it in translation--you can here.

Also be sure to read and listen to the work of one of the most famous female troubadours [or poet], the French Beatritz de Dia [living around 1175]. By the way, this is noted as "fl. c. 1175" by most sources even nowadays, and it comes from the Latin 'flourished [around]', or as we would say 'lived'. The 'c' is of course 'circa' or 'around'. Watch this incredible performance in Germany of her piece "A chantar", performed with ancient instrumentation and a costumed singer [!!] at the Musiktheater Dingo.

Listen to her poetry set to music here along with other medieval composers. Beatritz de Dia's poem 'A chantar m'er de so qu'eu no volria' is translated onscreen for us with the music here. Read more about her here as well, with another poem example.