So, how can one legitimately respond to such a question? First, I ask a few questions, such as:
- Was it legally recorded? If yes, was it a one-party or two-party consent? If no, they might need to be contacting legal counsel and not me.
- Is it a criminal, civil, or professional matter? If criminal, have they already contacted the appropriate authorities?
- What kind of recorder is it (e.g. pocket recorder, cassette deck, or answering machine)?
- What is the noise/interference like (e.g. hum, hiss, another talker, music, machinery, pops/clicks, or mobile/cell phone)?
- How loud is the desired voice relative to the noise?
- Is the original recording available? If so, what type of media is it on?
- Is there a digital copy that could be emailed for an informal evaluation?
There is no way to avoid the uncertainty due to differences in terminology, technical savvy, and the like, but going through this question and answer process usually does let me give them some useful feedback and some confidence in whether it is likely worthwhile to proceed or not.