Need help removing strange noise

I rented a music CD at the public library today and one of the songs has a bad spot. I tried burning a new copy as sometimes that’ll repair minor problems, but it didn’t work this time. I tried the Repair and Noise Removal tools in Audacity without any luck. I was able to isolate the source and attached an image of the waveform. I also attached an audio clip. Right after he says “luck” there’s some kind of glitch. Does anyone recognize what it is or if it’s a lost cause? Thanks.


I would have cleaned the CD myself. Glass cleaner and a clean, fresh towel. Never go 'round and 'round. Always rub from center out. There are other more extreme cleaning methods, but not on library disks. I occasionally have to pull fingerprints or peanut butter from library DVD movies.

Although that doesn’t sound like a regular CD error. A data error on the CD would cause muting to kick in. There would be a hole there, not distortion. Was the library’s copy original, or did the library have an educational copyright and make physical copies as they go?

I don’t know any way to fix that – turn that glitch into perfect music. A very old trick is to copy that same phrase from later or earlier in the song and cover up the error.

That’s advanced editing but it can be done.


Does the library have more than one copy, or is the copy available from more than one branch?

“Sorry, Mar Vista doesn’t have it, but Venice claims to have a copy on the shelf. Shall I get them to save it for you?”


What I would try doing is:

  1. Select the glitch (as you have in your image)

  2. Delete that section of audio - it’s quite short

  3. Just pop a temporary label there with Ctrl+B as a marker

  4. zoom out and use use the Repair tool on the audi surrounding the ex-glitch

  5. listen to the result to test its efficacy …


I guess it’s ripped from a vinyl. It looks like some high frequencies resonate over the vocal.

Here is a hint:

  1. select that region where the “glitch” appears
  2. make 2 copies of selection (Edit > Duplicate)
  3. invert data of 2nd copy (Effect > Invert)
  4. apply notch filter on 1st copy (Effect > Notch Filter…) /I used following settings: frequency=10000Hz, Q=0,4/
  5. mix & render the both copies of selecton (Track > Mix and Render), now we have the “noise” of high frequencies with inverted data.
  6. use envelope tool to compress by hand the elements you DO NOT want to substract from the original selection (see the scheenshot).
  7. mix & render the selection of compressed “noise” and original selection.

The result:


I did clean the disk. I thought about mentioning that after I posted. I tried everything I could think of.

It’s the only copy of the song in the library. Unfortunately we only have one branch where I live. They have a buffer but it’s not very good. It can’t remove scratches, it’s really just a cleaner.

The disk is a commercial CD, not a copy.

wax, I tried your idea, but when you cut out the glitch, some of the music goes with it.

vpd, thanks for sharing that. I got to the Envelope tool and that’s where I gave up. Your sample does sound quite a bit better though.

At this point I’m willing to wager it’s a scratch. My sister has a newer computer so I might try burning a copy on it and see what happens. I like that song so I’ll figure something out.

You could also try ripping the CD with a ripper that has advanced error correction, like .


I can’t believe it, I fixed it. I did kozikowski’s suggestion and copied two words from earlier in the song then cut out the bad spot and pasted in the new data. It worked seamlessly, I didn’t have to apply repair or anything. LOL Thanks to all for your help. Audacity’s awesome!