Panopreter Basic is a text to speech and text to mp3 freeware program with following features, it is a less-featured version, if it does not meet your requirements, try the standard edition Panopreter 64 bit or 32 bit instead.
However, if what you are looking for is speech to text converter, here is the one of the best online audio to text transcription service.
Read the review by TechNadu, and upgrade to the standard edition.
Text to Speech Software Review