Thanks for making this!
Minor quibble: the "Binaural Beat Machine" does not produce binaural beats. It plays two notes at the same time, to both ears, which produces an actual beat in each ear (pull off one headphone - you can still hear it). A nice example of how it should sound: http://en.wikipedia.org/wiki/Binaural_beats
Open source has a time and a place, but some things, like finished websites, are best left proprietary. There's a lot of thinking that's gone into this site. I think the #1 thing that would happen as a result of open sourcing it is that other people would just take the her work and creating clones, eroding her ability to make money from it (if she so chooses).
Choosing to open source something should be done only with a compelling rationale, and the downsides should always be carefully considered.
Furthermore, because of the high quality, someone is extremely likely to turn this into a paid mobile app and make money off of it (irrespective of the license it is released under-- unscrupulous people don't care about pieces of virtual paper).
I used a white noise generator app for a long time with my first child and this is far superior to what I had. I would have gladly paid several dollars for a solid mobile execution of this.
People that open source things do so as a gift to the community at large, and sometimes people just don't want to give away their property (intellectual in this case), even if they don't intent to turn a profit. Plus, leading an open source project can be quite stressful and there's also the time cost of actually supporting a community of people, if they gather around a project.
There are tons of downsides to open sourcing something but occasionally there's a significant benefit (or other motive) that drives the decision to open source and outweighs the negatives.
The site is fantastic - and the aesthetics of the background pics you chose are very well done.
A "mute all" button. I like having multiple layers of sounds open at once. Sometimes I need to mute them to watch a video or something, and it's a hassle to go through muting each one.