Hello, Ishumael,

Thanks for the clarification. Again, to try and understand this, let 
me restate the question as I think I understand it:

In digitizing a collection of audio cassettes to WAV file, the 
cassettes contain some confidential information that has been 
redacted by adding distortion in Adobe Audition, and then MP3 files 
have been created for public access with the distorted information included.

I would not trust that distortion could not be reversed to the extent 
of making the redacted material unaccessible.

What I have done -- with the clients' blessing -- is cut out the 
redacted material and replace it with a short 1 kHz beep that fades 
up and fades down fairly quickly. This lets the listener know that 
something was redacted, it saves the listener time since the entire 
duration of the redacted material is not included, and it is 
impossible to reverse. The only flaw in this is if you want the 
listener to know the duration of the redacted material, then you'd 
have to place silence of the same duration in the place of the 
redacted material.

I presume that the archives are retaining both a redacted and 
non-redacted WAV file of the material, as, at some point, the 
restrictions might be removed.



At 07:11 AM 2010-04-04, you wrote:
>Hi Richard
>Thank you, but just to explain our position. We have digitized from 
>analogue audio cassettes to wav. file for preservation and intend to 
>give access as mp3. However, before we do that we would want to 
>redact all the confidential information in our recordings. What i 
>would like to know is that:
>1. If we have distorted the audio recording or  is there a way that 
>the original distortion can be undistorted by using the same 
>software(adobe audition in our case) if the audio file has been 
>compressed from wav to mp3;2. If it can, what is the best method of 
>voice distortion in adobe audition without affecting the file
>Thanks for your assistanceIshumael
>--- On Sun, 4/4/10, Richard L. Hess <[log in to unmask]> wrote:
>From: Richard L. Hess <[log in to unmask]>
>Subject: Re: [ARSCLIST] Voice Distortion
>To: [log in to unmask]
>Date: Sunday, 4 April, 2010, 3:45
>Hello, Ishumael,
>If I understand your question correctly, there was once a WAV file 
>that was then encoded as an MP3 and the WAV file went away and now 
>you wish to reconstruct it from the MP3. Is this a quick assessment 
>of what you wish to do?
>If it is, I'm afraid that the MP3 coding process throws away 
>"inaudible" information or "barely audible" information, and I doubt 
>there is any way of getting that back.
>When you speak of "distortion" if that existed in the original, 
>there are some "de-clip" algorithms that are marginally successful 
>if the wind is blowing from the right direction in slightly removing 
>some forms of clipping, but, all-in-all, the experience I've had 
>with these have barely been worth the effort.
>It would be best to somehow re-generate the original WAV files, 
>preferably at 48 ks/s 24 bits for voice or 96 ks/s 24 bits for music.
>At 04:58 PM 2010-04-03, you wrote:
> > Dear colleagues
> > I do hope I find you well.
> > I would like ask for advice on the following:
> > 1. Is it possible to undistort a recording that has been 
> compressed from a wav file to mp3 and manage to listen to the 
> original recording if one was to use the same software (adobe 
> audition) to listen to the recording2.What is the best possible way 
> of voice distortion in adobe audition.
> > RegardsIshumael
> >
>Richard L. Hess                   email: [log in to unmask]
>Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
>Detailed contact information:
>Quality tape transfers -- even from hard-to-play tapes.

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
Detailed contact information:
Quality tape transfers -- even from hard-to-play tapes.