for text to voice:
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Text aloud mp3, this software can do the job, if you additionally install 'natural voice' along with default 'Microsoft Anna', you can get a fantastic human like voice (unlike robotic voice, which normal text to speech softwares produce)! You can save them to mp3 or wav formats too...
for voice to text:
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no idea!
If you have an audio version, there must be a text version somewhere,
its lot easier to get that text version than to do speech recognition without errors!