I moaned when my daughter received another stuffed animal for her baptism. And I have to admit, I kinda laughed thinking, "Wow, what am I ever going to do with this?" Her great aunt sent her a "sleep sheep" from red envelope. I hung it on her crib one night, and turned it on. It worked wonders! I know it this isn't voice activated... but it does hang on her crib for easy access and I can always find a large sheep in the middle of the night. It has four...? options - I think - whale noises, waves, rain, heartbeats. If anything, the rain static makes me go to bed easier when she's searching for a binkie in the middle of the night!
Good luck and congrats!