The time that it takes legal transcriptionists to transcribe
30 minutes of audio is going to depend on how comprehendible some speaks. If the audio is very comprehendible, then the turnaround will be much shorter. Harder to understand administrative hearings will take more work to transcribe, causing a more extended turnaround period. When submitting an audio file to a transcription service, note the quality of the speaker to judge the expected turnaround.