I thought I'd try to explain this concept for an app, where you record sounds and then set the pitch to play on a keyboard. This is not a mixing program but it could be used to save individual copies of melody files, imprinted with key signatures, etc cetera.

The primary component is to take the recorded segment from the user's voice, bells, real life sound effects, and to analyze a broad clip into a single note. This segment can be stretched, bent, and other computerized mechanical instrumentation (staccato, sustenance, manual pitch manipulation).

The point is maybe to be able to download an archive of nature sounds, and to turn each one into an instrument of its own while using such an App. Notice a clean GUI with minimal text in this design. Good luck, everyone deserves to have one of these and it should not be >33Mb to finish.