Removing Surface Cruft in Software?

I’m digitizing some of my father-in-law’s old jazz LPs from the 50s. They clean up pretty well in most cases.

On the current title. I’ve had to truncate a couple tracks where damage was too severe to correct. It’s a shame, because it’s a really good album (Anita O’ Day, “This Is Anita”).

Now I’m trying to preserve a track that has an isolated problem you can hear in the attached file. It sounds like there is foreign matter on the LP surface. What is this characterized as? (E.g. Noise?) And does anyone have any recommendation as to how to remove the scraping sound in Audacity?

Full disclosure: I will be writing about this in a blog I keep about digitizing analog source material and will give credit where credit is due.

Thanks in advance!

Try this excellent plugin written by Steve:

You might find this workflow tutorial interesting/useful:


Unfortunately the damage is too severe for that plug-in to help - the “noise” lasts too long. The plug-in is designed to handle relatively short bad spots rather than noise that lasts for several seconds.

Yes, bad noise.
It sounds similar to very bad surface noise, but looking closely there seems to be something very odd about it. At the point where the noise starts, the left/right channel audio signals go “out of phase” but I don’t see how surface damage would account for that. There’s also a marked ripple at about 7.6 Hz that kicks in just before the noise starts - it’s clearly visible (and reverse phase in Left/Right channels) toward the end of the audio sample that you posted.

If you record the vinyl again, do you get the same noise in exactly the same places?
Is the noise specific to that one album?
Does the noise occur in just one place on the album?
How long does the noise last?

@Steve: Wow, good analysis - you need to split to mono, invert one channel then mix and render to see it.

But I think that only the noise is (partially) out of phase - the actual recording seems to remain in phase (and is thus cancelled out, even during the noise burst). If you split to mono then mix and render the noise is still there, so it is not purely out of phase. Oh, and during the appearance of the sub-sonic out-of-phase ripple at the end of the noise burst the audio does come up in volume in the reversed-mix-and-render version.

Just guessing here, but the out of phase sub-sonic noise represents vertical modulation of the groove, so could the stylus have popped out of the groove for 3 revolutions? Is it a pressing fault?

– Bill

Pressing fault? I’m guessing my father-in-law bought it c. 1956. And, based on gnarly scratches in a couple other tracks, the album led something of a hard life. :slight_smile:

Amplify the track before splitting. You will then notice that the actual recording is cancelled out in the first 0.4 second (or so) and the final 0.3 seconds, but is not cancelled out from just before the sub-sonic out-of-phase ripple kicks in, up to the end of the noise. Weird. Is there a vinyl expert in the house?

To answer an earlier question, I have only encountered this phenomenon on the album in question, and it only occurs in a < 30 second section of audio. There are two short bursts, then the sustained occurrence.

If I can do so and not run afoul of attachment limits, I’ll upload the full section for more perspective.

You do know you can get that album on CD from

and on


I didn’t have the heart to tell my father-in-law half his LP titles were available on CD.

Sometimes people dont want perfection, they just want music to sound like they remember it.

Attached is a 7-second sequence from the track containing all instances of the phenomenon.


Like my son for instance …

When I digitized my old 45s many of which had had a very hard like on our old jukebox, I worked hard to clean them up removing all the pops/clicks etc. When I gave him a copy of the set he complained saying that he preferred them the way they used to sound on the juke box - with all the “noise” :unamused:


Personally when I digitized my LPs I preferred to replace them with CDs where available (at a sensible price). Though in some instances the recordings had been “remastered” - and the re-masters were not an improvement on the original, in which case it was back to a vinyl transfer.

My particular pet hate is recordings that were originally mono being re-issued in a faux stereo - but that’s easily fixable by squishing the two “stereo” tacks back to mono.

Good luck with the continuing project and have fun with it (I’m now working on my wife’s LP/tape collection),


The longer sound sample is 307 KB. Too big?

Like father like son :smiley:

I don’t think that we need a longer sound sample.
The noise is very severe and it is “broadband noise” (a wide range of frequencies). We are unsure of the cause of the noise, but as it is in a few specific places on one album only, the problem is clearly with the vinyl and not with your equipment. It may be due to a bad pressing, or perhaps someone has attempted to play the record with a broken stylus that has badly scraped the groove (and tried in several places before giving up). Whatever the cause there is not much that can be done to repair it.

The first thing that I would do is to use the Amplify effect to bring the level up a bit.

Broadband noise cannot be “filtered” out because filtering will also remove the sound that we want to keep.
We also noticed that there is some low frequency modulation of the audio so we had better remove this first.
Use the high-pass filter with a frequency setting of around 40 Hz and a slope of 6 dB per octave. This should be applied to the entire track.

Spectral processing techniques, as used by the “Noise Removal” effect probably give the best chance of improvement.
Don’t expect miracles - the damage is very severe. At best we may be able to make a little improvement.
See here about the Noise Removal effect (after reading that, the next part should make sense).

A problem we have with using the Noise Removal effect is that we need a “noise only” sample to create the noise profile, but we don’t have one. So the first thing we need to do is to find or make some noise that has a similar character to the noise that we want to remove.

To create a noise sample, I created a new stereo track (Tracks > Add New > Stereo Track), then selected about 4 seconds of this empty track (click and drag along the track). Then I used the Nyquist Prompt effect (Effect menu) to generate some customised noise.
Copy and paste this code into the text area of the Nyquist Prompt effect:

  (mult 0.05 (noise))
        (eq-lowshelf (noise)1000 -12)
        (s-max 0 (hp (lp (noise) 80) 80))

This will generate some noise that is similar in character to the noise on the track.
With this noise selected, open the Noise Removal effect and click the “Get Noise Profile” button. You won’t see anything “happen”, it will just make a “profile” of the noise and then exit.
Now select the damaged area of the track and bring up the Noise Removal effect again.
Try these settings:

Noise Reduction: 24
Sensitivity: 0
Freq Smoothing: 200
Attack/Decay: 0

Then click the OK button.
BEFORE you loose the selected area, apply the Amplify effect with “Amplification dB” set to about 4 dB. (this will compensate for some of the gain loss that occurred with the Noise Removal effect.

It should end up sounding something like this: