This tool base by CMU Sphinx, which provides an open source speech recognition toolkit out of CMU.
It is actually a complimentary and online tool. You just upload the audio file in below, then click “refresh” to convert and download the end result in a text file. Now only encourage recognition English.
This tool will take a longer time to convert, so please be patient. Maximum file upload cannot transcend 3M. We estimate that even convert 1M size MP3 file can take 4 5 minutes.click here for link