Echo or Artifact?

I've  been working recently on some early acoustic recordings and trying to clean them up.  In the process of removing some of the noise on a track, John McCormack, 1910, mp3 link below, an echo emerged.  It is not sonically offensive to my ears and does not appear to have the hollow metallic sound I associate with noise-reduction overkill, but I am wondering whether it is sonic ambiance that was masked by noise or an artifact induced by noise reduction.  Other than the subjective judgement of one's own ears, is there a way to tell the difference?  If it is an artifact how might it be avoided as I tried to proceed in a quite careful, incremental manner?

A second question that arose in connection with the same file, but not related to artifacts real or imagined is the use of the cool edit/audition click-pop remover, one of my favorite tools but tedious to use by hand.  Basically, after I finally isolated, with difficulty, a band that contained most of the periodic scraping sounds associated with an old 78's rotation, the only way I could minimize the noise was to either: 1. cut the whole band out, which I was reluctant to do, or 2. use the click-pop remover, step by step, inch by inch, which was time consuming as well as tedious.  So the question is, are there settings on the click-pop remover that would accomplish the same thing?  I tried the most extreme settings and the results were not the same.  Or is there some other approach that one might apply to a band of noise that would remove sounds like scraping?

Any helpful comments will be appreciated but it is not a frantic rush as working on audio is something I only do on occasion.  Thanks.


zipped copies of the before and after files in mp3 format are here; they are small bc the audio range and quality of the track is limited and wouldn't benefit much from less compression.

http://www.mediafire.com/?byyxsgwldhj

I had a brief look at the before file, and did what I usually do to these - ran the declicker over it once letting it choose the settings, and then, using a high-number FFT, did a couple of NR passes over it. In other words, I didn't take it all out at once. And with a file like this, I don't think that realistically, you can take it all out without some sort of artefacts, whatever you do. Also I reduced the bandwidth of the end result, because everything above about 5kHz wasn't adding anything that I wanted to hear!

And doing that resulted in a file that on these monitors sounded rather better than your processed one, even though it was by no means perfect. So I'd try the NR with a much higher FFT value set, for a start - this will almost certainly improve things. And do the bandwidth limit as well.

I'm not sure if it's artefacts or an echo you've got, quite frankly - but I'm more inclined to artefacts, simply because of the relative insensitivity of recording instruments of that period, and that it would almost certainly have been a 'gather round the horn' job.

You don't state what version of AA you are using, but a lot of this stuff becomes easier on anything beyond 2.0, and 3.0.1 is now pretty good, because the spectral healing tools don't cause random crashes any more.

Having said all of that, I'm certain that the person best-equipped to answer your questions about this, especially in terms of repetitive noise removal, is Andrew Rose - if he spots the thread.

+-Thanks for your help.  I kept looking at replies to your posts at the login screen and that nothing showed up so I did not realize there was any feedback.

Your point about the echo is exactly why I was wondering about it myself.  I doesn't seem likely that this sort of recording would have been that sensitive.

Also, thanks for your tip; I just saw some of andrew rose's old posts in which he mentions using high ftt's and I tried that with some subsequent files and got somewhat better results but I did not go back and try it on this.  You are likely right about nothing useful beyond 5K; I was just trying to keep as much as possible in terms of range but I guess you also need to know what to fold and call it a day.

PS I was  using audition 3.0 and I had some multiple passes on the file