This App I have to recommend for not only Mac OSX but also the iPhone.
White Noise by TMSOFT
I use this app most every day. As an ADD Technical Director, I like noise but nothing to distracting. With this program I can customize what I hear.
This is pretty straight forward app so I won’t waste your time rambling.
I use it on the iPhone at night when I sleep as well, and on business trips where I share a hotel room with a co-worker who can out snore me, this was a sleep saver. I am partial to the Amazon Jungle while I work and Rain storm or Airplane while I sleep.
Check it out on either APP store for Mac or iPhone.