We used to have a similar in-house developed audio feedback in one of our apps [1]. The engagement rate was low. We replaced it with the standard email feedback and we got an order of magnitude more feedback. Plus with email, you automatically get the ability to answer back and communicate with the customer. In my opinion users prefer UX concepts they are used to, even if they are less efficient. But it probably also depends on the app type and its audience. So best to test it for yourself and see what works.
There was also a startup doing this [2]. Looks inactive since their iOS SDK is "coming soon" for already a year.