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Last year's soccer World Cup in South Africa brought about many vuvuzela silencing tools. What are the characteristics of vuvuzela noise that allow it to be silenced? What are some of the common techniques used for silencing vuvuzelas?

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It is not likely that you are going to be able to work around this using EQs, while leaving the rest of the sound intact / not weird sounding. The vuvuzela sound is quite broadband, as far as I know. (Never measured it though.)

It is neither likely that many facts are known about the characteristics of the vuvuzela. That means, probably the best way to get around with it, is: get your hands on a few of these annoying things, sample them, do some frequency analysis and see what their characteristics are.

Since the hum is the result of 1000s of vuvuzelas, you might well end up trying to work around it with a noise reduction plugin that can sample noise. I can recommend iZotope RX Denoiser for this purpose, although I don't know in advance what the results are going to be like. I would play around with it for some time though.

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There were plenty of tools created for doing this, and all of them that I saw used EQs. They worked quite well. Given that most of the other sound during the world cup was speech, removing the vuvuzelas wasn't an issue. Removing them from music or something might be, but EQ definitely works for the World Cup audio. –  Brad Jan 5 '11 at 21:46
    
@Brad, some of the solution include other techniques, such as multiband compressors. Here's an academic example of someone who used fast Fourier transform to remove the vuvuzela noise: mathworks.com/matlabcentral/fileexchange/… –  Kim Burgaard Jan 5 '11 at 22:18
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The characteristic that allows the vuvuzela to be isolated in removed is the fact that the sound is constant pitch. So removing it is a fairly simple exercise in EQ:
1. Identify the base frequency (around 235 Hz) and harmonics (the strongest is the first harmonic around 470 Hz).
2. Add an EQ filter at each of the frequencies of step one with a narrow Q (to minimize impact to sound other than the vuvuzela) and turn the gain way down.

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As an alternative to EQing, couldn't a sample of the vuvuzela be played against itself with inverted phase to lower the amount with interference? –  Nic Jan 5 '11 at 0:11
    
I meant a feed, not a sample. –  Nic Jan 5 '11 at 0:17
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The vuvuzela's are not precision musical instruments; the hum heard during the world cup was the result of perhaps thousands of vuvuzelas. So it would hard, if not impossible to define the exact inverse phase. A better approach might be to employ fast Fourier transform to identify and suppress the frequency band that the vuvuzelas tend to fall within. The plugin maker Waves well as several other plugin manufacturers released plugins specifically to suppress the vuvuzela sound during the world cup –  Kim Burgaard Jan 5 '11 at 0:54
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Not wanting to be funny, but WAVES released a preset pack for a processing chain to get rid of vuvuzela for post when the world cup came out. A friend of mine was doing extensive editing on footage for some tv stations and he said it actually works. Might be worth to give it a shot? if you have an iLok you can even get a 15day trial!

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WAVES vuvuzela preset pack page –  Thies Heidecke May 22 '11 at 23:06
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Vuvuzelas share the following common denominators:

  1. same length
  2. mostly plastic (at least at the World Cup)
  3. same foul tonality
  4. fundamental pitch is prominent, with a fairly simple series of harmonics

All of this means some effective DSP can extract and banish the Vuvuzela's characteristic elephant-fart sound given a decent spectral fingerprint.

I was quite impressed by Audionamix (the French workers of acoustic magic) who came up with probably the most impressive operational system -- in 48 hours, apparently -- for minusing the Vuvuzela drone from broadcast audio; they demonstrated it in operation with some sample audio from German TV and later Canal+ (in France) implemented it into their signal chain for live broadcast. Unlike simple multiband compression and EQ, they repurposed their existing instrument extraction techniques (already available for those looking to upmix 2.0 masters to surround) and customised it just for Vuvuzela extraction.

They still have their minisite online at http://audionamix.com/Vuvuzela/; the statistics make for some interesting reading. Their demonstration video's also available on YouTube if you've not already seen it.

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