K.G.
We were given a sound machine when my daughter was about 8 months or so...she has always been a light sleeper so i def. think that it helps keep her sleeping while we are up, moving about, watching movies, conversing etc
there are sound machines that have other options that just white noise and i highly encouarage that kind, after awhile the while noise just get to you. we use the ocean waves, or rain etc...
in fact, she is 3 now, and there are several nights of the week when we still use it....