In 2015 Su collaborated with Sian Croose to compose Harmonium. An experiment in vocal sound, it was created by layering voices using interlocking rhythms and harmonies. Harmonium 1 was written by Sian Croose for Vocal Invention Norwich in 2009, Sian and Su  are now working together on this project, each writing pieces for women’s voices – influenced by music as diverse as Meredith Monk and Baka women’s rainforest singing.
Harmonium was performed in the Bath International Music Festival and Norwich and Norfolk Festival 2015
Workshops are offered to experienced female singers giving participants an opportunity to experience this kind of singing in the round – where the parts make the whole.