All system sounds can be found inside the `/system/media` folder.

Different to the `/data` partition the `/system` partition can be read with normal user permissions so you can easily copy those sounds; you don't need any source code (whyever would you need code for that?).

If you'd like to get an application specific sound then open the apk as a `.zip`-file and look out for the `assets` and `res/raw` folders.