Distort voice to hide talker identity as much as possible
To preserve the talker's identity for privacy reasons, I would make available for listening a distorted version of the original audio file, while using the original one for real recognition to improve the system.


This won't work.

The point is that the whole job of your speech recognition algorithm is to figure out which "components" in your audio signal are of significance, and what they mean, and to ignore things that are irrelevant to the textual content, namely identity of the speaker.

By wanting an algorithm that removes a dominant aspect of the signal but preserves the original speech content, you'd first need to have an algorithm able to tell the content-wise important components from the unimportant. That would be the major part of your speech recognition algorithm, which is exactly what you wanted to build in the first place.

Generally, this sounds like you want to do something that other companies literally spent several millions on with a small team and little experience. I'm afraid that's not really a promising approach.