Removing thumps and bumps

I have a solo violin recording that’s marred by several loud microphone thumps, bumps, and scrapes. They’re longer than clicks or pops, but still impulsive and not amenable to the noise filter effect.

I’ve already discovered that replacing them with silence is pretty disruptive to the sound… about the best I’ve been able to do so far is use the envelope tool to modulate down the gain for one or two tenths of a second (duration of the thump).

Are there other techniques that experienced folks use to supress noises like these? In searching here, I’ve read about a “Repair” effect, but I don’t see it in the dropdown menu on the 1.2.6 I’m using (Windows version).



The Repair effect was only introduced in 1.3 - it may not be sufficient as it only fixes a maximum of 128 samples (so the time duration will depend on whether you are recording at 32-bit, 16-bit or whatever). The repair is done by interpolating from the neighbouring waveforms. The process is manual not automatic, you would need to identify each thump (as you are already doing) and then zoom in till you can see the individual sample points. BTW don’t be put off using the Beta - 1.3.7 is pretty mature and stable now, I use it all the time.

In 1.2 (and indeed in 1.3) you can fix longer sections of “noise” by using the Pencil tool to manually redraw the waveforms (i.e. you do the interpolation). I used to fix clicks this way (v. hard work) until I discovered better ways of fixing them.


It would be possible to attenuate a low frequency thump without affecting the high frequency violin by using equalization.
1.3 has a graphic equaliser built-in. A “classic” 15 band graphic equaliser plug-in for 1.2 can be downloaded from here.

It may be possible do a repair by cutting out the noise and replacing the silent gap with a copy of the signal immediately before (or after) the noise occurred. If successful this would remove the thump entirely.

If you post a link to a short (~10seconds) extract of your violin with thumps and I will have go using both methods.

Hi. Mr. Wet Blanket here.

People smacking the microphone stand is almost always fatal to the performance because it drives the microphone itself or certainly the microphone preamplifier into a non-linear region or outright clipping. In English it means the stuff is not only disruptive to the ear, but it very likely has damaged the desired performance underneath it as well.

I agree you might be able to suppress the thumps with the low filters, but I bet you’re also required to go in and shore up the notes as well.

What are the chances nobody is going to notice you did all that? The stitches and surgery don’t show until you try to smile. A turtle, an archangel, and a mongoose walk into a bar…


Like I said a cut and paste may be possible: it depends what the violin is doing around the time of the thump and the thump duration.

I will have a bash at making a repair if EddyKilowatt posts a link to some audio.

This is me watching the thread.

Do you know how long the performance is? I mean the whole thing, not just the part you’re going to patch.


Hi, thanks for the suggestions everyone.

Haven’t had a chance to work on this project for a few days, but I’ll try again later this week. This is not a hi-fi recording, it was just my son with a Zoom H2 sitting fifteen feet away from a teacher playing a fiddle tune… so I don’t need a seamless repair, I just wanted to reduce the audible assault by a bit.

The low filter should be a good place to start, nothing on the fiddle below 196 Hz (in principle at least). I’ll experiment with the pencil tool and perhaps cut and paste (I sort of knew that was an option, but also that getting a thumpless clickless ‘paste’ is not trivial either), and perhaps with 1.3 as well (was just avoiding it due to my low experience level, really should stick to sturdy beginner tools at this point). Again, this is just a student’s teacher tape… we’re not restoring The Last Supper or a rare Fritz Kreisler recording!

I don’t have a site to post sound clips; is there an upload area on this board? (Haven’t looked).

thanks again for all the suggestions,

p.s. the performances are mostly just a minute or two each

Some people on this forum use accounts to send files, (yucky casino adverts, but “lite” version is free),
other file sharing sites are available.

If you can post an mp3 of Yehudi on sendspace or similar site I will have a bash at cleaning it, (if it is only 2-3min post the whole performance).

Like Kozikowski says repairs are difficult to do without joins being noticable, so be warned the result could be Frankensteinian.

(You could email me the mp3: I’ll send you a PM with my email address).

I’m clear this is counterproductive, but the full quality WAV Exports are easier to clean and/or manage. MP3 introduces its own errors.


Agreed the the original WAV would provide the very best quality but a 2-3 minute WAV is probably too big to email (over 10Mb).

I have tried applying the high pass filter to the thump. It helps, but does not cure it. I will try some more settings…

I am trying to minimize a thump caused by a flaw in the vinyl of a record, the best setting I could find was High Pass Filter 250-300 Hz -12 dB, with the shortest possible selection. Repair is no use here, because the artifacts are ~15 msec. long. Larger flaws might require a lower frequency setting.

Could you post a short sample in WAV format.
Select about 4 or 5 seconds that includes a thump, then “File > Export Selection”.
Attach the file using “Upload attachment” below the message compose box.

Yahoo Mail supports up to 25MB. If you make it mono, it might fit. Let us know. I can post it on in the original quality so everybody can have a crack at it.


I found that I should first Normalize the track to eliminate DC offset only. (I have been using an old Philips SA 261 to record, it’s not perfect.) Then selecting the section with the thump, keeping the selection points where the waveform crosses the zero point. Then apply High Pass Filter. For these thumps 300 Hz and -6 dB worked for me. However, I had to undo, reselect, with slightly different selection points, and apply the filter again, because the filter sometimes didn’t match the waveforms at the selection point.

Absolutely. You should do this before any processing or editing.

I’ve posted a new plug-in effect here:
This filter effect can automatically crossfade the effect in and out, thus avoiding clicks even if the selection does not start or end at zero crossing points. You will need to make the selection long enough to accommodate the crossfade at the start and end of the selection. A crossfade duration of 20 or 30 milliseconds will probably be about right, but please to experiment to see which works best for you.

This is a brand new plug-in, so any feedback about it would be much appreciated.