Does audio pre-processing improve transcription? Such as by changing speed \ pitch \ etc

[brianb01]

Would using an application like Audacity or audio processing library to slow down the speech or change the pitch or otherwise altering the audio have a positive impact on transcription? Assuming the audio was recorded at a high "resolution".

The use-cases I am think of might be slowing the speech of a speaker who talks very rapidly or not very clearly.