i have a 3 month old and play him all manner of tunes from the hi fi. studio one, instrumentals and otherwise, definitely seem to go over well, but the only thing that has really freaked him out so far was a set of ska scorcher instrumentals, i think it was just too intense. question though...why are you only looking for calm sounds? i'd start mimicking the sounds that she is bound to hear in the future! you don't have to blow the baby away with bass or anything, but lively stuff can be enjoyable too!