I use Dragon NaturallySpeaking 12 Premium.
Yes, Dragon NaturallySpeaking allows you to Transcribe a recorded audio file. See the attached image.
However, let me warn you that the results are not what you would expect or hope for. There is likely to be several errors, missed words, mis-recognized words and if you want a reasonably good transcription, I think you would be disappointed.
I have tried it several times to get a reasonably good MP3 to be processed into text by Dragon NaturallySpeaking without human intervention, but the results contain far too many errors and the subsequent correction process to tidy it up simply takes too long.
The reason for this is multifaceted; the voice model of the speaker may not be available to you (ie - it is not trained to his voice), the MP3 quality may have a lot of background noise, or the microphone was not of a good enough quality or it may be too far away from the speaker's mouth, or he may be speaking too close or too directly into it and it's capturing his breathing sounds and he may slur his speech, or not pronounce words carefully (ie the speaker is not speaking specifically for speech transcription). There are many factors that contribute to accuracy or lack of accuracy.
Although Dragon NaturallySpeaking has really come of age and doesn't really require that much training in version 12, it does require that you enunciate the words reasonably carefully, without speaking too fast but rather speaking naturally and of course you need a fast laptop as it is quite CPU intensive.
Those people who have used speech transcription will tell you that the most accurate and efficient and effective method is really listen and read back. What that means, simply is that you listen to what the speaker is saying on the MP3 for example and then you speak into a good quality microphone, ie you act as a go between. If you do it this way, then Dragon NaturallySpeaking will give you outstanding results.
However, please take note, it takes approximately about an hour to transcribe 10 minutes of MP3 if you used the listen and read back method.
It is also Critical to make sure that you use a high quality microphone that is attached to a good quality sound card or a good quality USB sound pod.
Another way, is to pay for someone to transcribe for you. Just Google for transcription services.
After all is said and done, you perhaps may still want to just try using Dragon NaturallySpeaking to process the MP3 to see the whether the results are adequate enough for you.