Honestly, this is one of those things that I'm never going to use because it's Web 2.0 and doesn't need to be. Your core functionality is cool: I definitely would like something that allows me to mix background noises. But why am I signing up for your service? That has nothing to do with what I want from your app. That just gets in the way of using your app. Why is there integration with Google Drive? That has nothin…
I agree partially with >But why am I signing up for your service? That has nothing to do with what I want from your app. That just gets in the way of using your app. It would be cool to have an explanation of what signing up does (for now, there is just a button that you can click without really knowing why).
You can find more info here http://www.noisli.com/features (link bottom of the page) and here http://blog.noisli.com/introducing-the-new-noisli/ (our official blog). Hope this helps :)