Anyone knows any of these?

[crazy_diamond]

I had heard a radio commercial for this concert, and after it has took place, it occured to me that I'm enticed by the piece that was played on the commercial. I looked the concert's webpage and that was the repertoire:

Georges Aperghis - Petrrohl for 6 voices
Fredrik Zeller - Commissioned piece for vocal and instrumental ensembles
Tayseer Elias - Commissioned piece
Salvatore Sciarrino - L'Alibi della parola

The piece i've heard, had a choir singing repeatedly something like "siiies! siiies!" ( but the harmony changed and modulated ), and at the background was a single violin or viola.

I know its a long shot, but if anyone recognize it, please tell me so I can listen to it properly and get it out of my system,
Thanks!