You can listen to it by going here to WFMT.com and clicking on "Listen Live."
WFMT broadcasts all opening nights of the Lyric -- sometimes live, I believe, though in this case the opening was last night, so this is recorded. The cast mixes members of the Lyric Opera company with guest performers. For this production, as an example, Billy Zane will play the role of Captain Von Trapp.
Here's a brief preview