If we rewind your audio 3 to 5 times and still don’t feel sure that we’ve correctly been able to decipher a particular term, it’s marked as unintelligible. The term is NEVER guessed.
With general conversation, it can be difficult enough to capture the true meaning of one’s speech with all the variances in intonation, phrasing, diction, jargon, and idiosyncrasies unique to that speaker. This holds true even between the familiar, such as family members and the best of friends.
How many times in your life have you had to say:
“No, no, Sarah; I didn’t mean it that way!”
…and that’s when the listener has heard every word that you’ve said!
Consider the disaster that could happen, then, should a transcriptionist guess at something a stranger over an audio tape has uttered, when they don’t have the benefit of body language, lip-reading, or any prior knowledge of the speaker to assist in their interpretation.
So, despite a transcriptionist’s familiarity with your particular industry, terminology, and contextual clues, there still remains too much room for error to risk a “guess” at any phrase. And so, if there are any “unintelligibles” present in your document, they’re due to a lack of utter certainty on the part of the transcriber.