Related to this question: http://apple.stackexchange.com/questions/126458/what-cable-do-i-need-to-go-ipad-audio-out-to-macbook-air-mic-in which is asking about cables to record iPad audio on another device. 

This question is: is there a way to record audio generated on the iPad on the iPad itself? For example, are there any audio recording apps that can record in the background while audio is being created in another app? 

It's a bit hard to search for as there are a lot of apps that allow you to record audio via the external mic, but I'm specifically looking to record audio generated from the iPad itself (such as from a synthesizer or drum machine app).