You may not recover missing sectors

I think the point at issue here is whether the prosecution's enhanced version presents the information as being clearer than what the defendant actually heard in the original environment where the recording was made.

That's not really the case with partial fragments from a disk they tend to be presented 'as is' rather than in an enhanced form.

I beg to differ, specifically in cases where recovered file is a video, audio or image file, and a reconstruction or "enhancement" is often attempted.

One may claim they only saw/heard the "broken" material, not the enhanced one.

I think the point at issue here is whether the prosecution's enhanced version presents the information as being clearer than what the defendant actually heard in the original environment where the recording was made.

That's not really the case with partial fragments from a disk they tend to be presented 'as is' rather than in an enhanced form.

The cases I've worked at the Judge wants to know what was done to the tape for enhancement.

If you explain you do a normalization, then drop out frequency (insert number) then a 5db gain on section 305 of the tape, usually they are good with that.

Really it parallels CF work. If you are competent in what you do, confident in the skills you possess and can articulate that to others, they tend to share your confidence.

What a Judge doesn't want is you telling then what to hear, you cant start a tape and say see where he says (this) you play it for them a few times (usually looped) and then if you are asked what you heard then you say and you may have people who think along the same lines as you do. Sometimes an enhancement is not as good as a slow. You can slow things down to the syllable and you can clearly make out that a word is not the word they think they heard.

Enhacing audio can be crucial. There are few to tricks to apply to improve audio quality for voice and speech recognition. 1) Identify the predominant resonant freq of the speech & apply a resonant filter in that range.
2) Cut unnecessary freqs with a Band pass filter.
3) Boost the audio file(or increment the gain).
4) In extreme situations, try an FFT analysis, and reconstruct the partials as you need. It is also good to use phonetic software to get && analyze the formants of the speech, specially to understand obscure passages.