Is this salvagable?

Randy Brown wrote on 11/4/2009, 2:42 PM

A client came to me today with a CD copy of a digital recording he wants cleaned up. It is almost not intelligible but it is very important to the client (he's a policeman that says he was fired unjustly and the recording can prove him right.)
I am willing to pay for help on this. If interested please listen to the mp3 sample at soundclick.com/GRB53 ... it's at the top titled "conversation".
If you think you can help I can email you the uncompressed file.
Thanks very much,
Randy

Comments

johnmeyer wrote on 11/4/2009, 3:45 PM

I was able to get rid of the raspy clipping, using iZotope RX's declipper. I tried various EQ and compression schemes to try to reverse the phone-line effect. I also tried Nero's "Band Extrapolation" feature which sometimes can synthesize fake frequencies for band-limited audio like AM radio, phone conversations, etc.

So, the declipper worked great and got rid of the nail-scratching distortion, but various attempts to do an inverse phone-line effect only made the speech a little better. Whatever device recorded this, it had a very effective band filter and there just isn't enough material outside the roughly 1,500 Hz. peak to do much with.

Randy Brown wrote on 11/4/2009, 3:56 PM

Thanks John, when you say a little better do you mean understandable/intelligible?
Thanks again very much,
Randy

RalphM wrote on 11/4/2009, 4:01 PM

Randy,

With an assumption that your client may have to go to court to get his job back, it would be good for him to check the rules of evidence that would apply. Atering the original recording in any way could be an issue.

If it is a non-court proof, that could be a different story. ..

Randy Brown wrote on 11/4/2009, 4:15 PM

I don't know if it would go to court or not but when I asked him if he could bring me the digital recorder it was recorded on he said no (he brought it on a burned CD).
I was thinking though that court submitted stuff couldn't be edited but could be "enhanced"...no?
Thanks very much Ralph,
Randy

RalphM wrote on 11/4/2009, 7:14 PM

I think that's a qwuestion for your client to answer, Randy. As a police officer, he should know some prosecutor that could provide an answer pretty easily.

Ralph

musicvid10 wrote on 11/4/2009, 9:39 PM

Randy,
1) The impression provided by johnmeyer is about the best you are going to get. He has more knowledge than I do, and I have done audio restoration work for over 30 years. My impression is that you may be able to improve, but not salvage the audio I listened to from your link.

2) I am not going to offer you or your client legal advice, because I am not qualified to do so. However, my impression is that if enhanced or edited audio were to be introduced in a legal proceeding, you (the editor) would almost certainly be called as a witness. Also, the unedited, unaltered original files would certainly need to be provided to the respondent during the discovery phase.

johnmeyer wrote on 11/4/2009, 11:17 PM

I tried, and I can understand a little more of it, but I'm not sure it would be useful to anyone. Here's a link to the "restored" snippet:

Restored conversation

I used iZotope RX's declipper.

The then used iZotope's spectral repair to get rid of other distortion that the declipper didn't fix.

I then used Sound Forge's Paragraphic EQ, starting with the Anti-DTMF talk-off preset. My idea was to reduce some of the energy around 1,200 Hz.

I briefly fiddled with various NR settings in SoundForge and iZotope, but didn't feel that they added much (or, I guess, subtracted much).

[edit] For whatever reason, the GetDropBox link above doesn't seem to work, even though I've tried uploading twice. So, here's a link to the same file via YouSendIt. This link will only be good for seven days:

"Restored" audio file

apit34356 wrote on 11/5/2009, 3:50 AM

I played JohnMeyer's changes thru VLC, turn-on the EQ with Soft settings and it sounded a lot better. So I think John's work is real close.

Jeff9329 wrote on 11/5/2009, 5:35 AM

Randy:

I can understand most of the clip provided. I slowed it down a little and used DPC. Your client could probably help translate all of it. When you transcribe the first part, and then read along as you play the file, it's easy to understand.

I don't think full restoration of the audio has as much importance except as a backup to a transcription of the conversation.

Jeff

Randy Brown wrote on 11/5/2009, 7:23 AM

Thanks to everyone for your input....especially John for putting so much effort into this!
I'll ask the client later this morning if John's clip would be acceptable but I have my doubts (John I will contact you if the client finds it acceptable).
I took musicvid's advice and googled "forensic specialist audio" and sent a .wav to the company listed at the top (BEK TEK LLC) to see what they say.
I'll report back with the results.
Thanks again everyone,
Randy