Getting rid of audio buzz help at DVinfo.net

Herm Stork · August 4th, 2012, 04:19 PM

Using Vegas 10...I'm trying to reduce a buzz in the audio track. I have attached a sample. Thanks in advance for any suggestions.

Don Bloom · August 4th, 2012, 08:11 PM

Kinda sounds like a ground loop. 60mhz. Try the 20 band graphic eq, pull the sliders on either side of the closest to 60 and see what that does. Do it at clip level so you can hear it then once you find it, you can set it at track level or the Vegas mixer.

Chris Harding · August 4th, 2012, 09:43 PM

Herm

That is definately mains hum and it sounds pretty constant too so it should be easy to kill on the audio plugin. As Don says, the GE should pull it out ...Just open the audio track FX and in the equalizer select Low Shelf tab and set the frequency to say 100hz and then take the gain (next slider) right down to about -12db or more .... you might have to take the frequency a tiny bit higher as there could also be harmonics from the 60hz signal that repeat at 120hz so maybe go to 150 to cover it???

The same advice works brilliantly for wind noise too!! I set the frequency to 400hz and it kills 99% of mic wind noise...useful to know

Chris

Seth Bloombaum · August 5th, 2012, 09:19 AM

Yes, the noise produced when different systems are connected together that don't share a common ground. Any stray electricity will seek to ground, commonly called "ground-loop hum". If recognized at the time of recording, it can usually be completely fixed by using an isolation transformer (The Sescom IL-19 is very popular for this), or, using an xlr barrel adapter that lifts the ground.

It's not a simple tone (sine wave) at 60Hz. Meaning, that it has multiple frequencies that are based on the fundamental tone of 60Hz.

So, use the narrowest filter you can, and dip at 60, 120, 180, 240Hz etc. Multiple filters may be required, depending how loud the noise is relative to content.

Ron Cooper · August 7th, 2012, 06:55 AM

Herm, I' ve just come across this and as it is a constant even noise it should be quite easy to remove.

There is a freebie sound editing program called "Audacity". Download it & open your track in Audacity & make sure there is some clean noise only, - (like the file you sent). then select a few seconds of the noise only, by dragging the hand from left to right, and under the Effect tab select "noise removal" /get noise profile. Then go back & select the whole track or a sample portion of it to try, and then under the effect tab/noise removal (if needed), drag the slider towards "More" - about 80%, and then click "remove noise"

This should do the trick, but you may need to experiment a bit for optimum results. - ie. The amount of noise removal on the slider, as while it is quite effective it can produce artifacts in the overall sound if you go too far.

Hope this helps,

RonC.

Magnus Helander · August 7th, 2012, 02:37 PM

On thing that WILL take care of your buzz is Izotope RX
iZotope RX - Complete Audio Restoration: Declipping, Declicker, Hum Removal, Denoiser, Spectral Repair, Restore, Remaster, Download
There are two versions - not sure which one you will need for the "Remove Hum" and "Spectral Repair".

This plug is outstanding and I use it all the time to clean up audio from office environments with airconditioning and other background noise.

/m

Gints Klimanis · August 7th, 2012, 02:57 PM

The methods mentioned before will work. Slightly more manual labor will help eliminate the guesswork.

Take a spectrogram (reasonable resolution, such as 2048 pts or more) of preferably at least a second of silence + hum. If you have a low frequency hum, look for a peak at 60 Hz (50 Hz in countries with that A/C frequency) and multiples of that : 120, 180, 240 300 Hz. Use a Notch or a parametric filter set to 60 Hz with a very high Q (20 or higher) (Q is sometimes expressed as Bandwidth, so specify a very small bandwidth) and BOOST by 10 dB. If the hum is twice as loud, you have identified the correct frequency. Then, cut by 10-20 dB or more. Repeat procedure for 120, 180 , etc. Hz, though the amount of cut will be less. Judge by the spectrogram.

If you don't have a spectrogram, you can hunt for the frequency with a boosting parametric filter. Just boost by 20 dB and a lower Q/high bandwidth and sweep it around in frequency. This is a hunt or miss procedure and much harder than using a spectrogram. When you find the offender, raise the Q/lower the bandwidth to avoid affecting adjacent frequencies. Finally, replace the boost with a cut.

Herm Stork · August 8th, 2012, 10:50 AM

Quote:

Originally Posted by Ron Cooper

Herm, I' ve just come across this and as it is a constant even noise it should be quite easy to remove.

There is a freebie sound editing program called "Audacity". Download it & open your track in Audacity & make sure there is some clean noise only, - (like the file you sent). then select a few seconds of the noise only, by dragging the hand from left to right, and under the Effect tab select "noise removal" /get noise profile. Then go back & select the whole track or a sample portion of it to try, and then under the effect tab/noise removal (if needed), drag the slider towards "More" - about 80%, and then click "remove noise"

This should do the trick, but you may need to experiment a bit for optimum results. - ie. The amount of noise removal on the slider, as while it is quite effective it can produce artifacts in the overall sound if you go too far.

Hope this helps,

RonC.

Ron and others,

Thanks for all of the suggestions. I played around in Vegas and couldn't get it sounding the way I wanted, so I downloaded "Audacity" and that did the trick!

Regards,

Herm

Ron Cooper · August 8th, 2012, 06:43 PM

Thanks for letting me know Herm. Yes, Audacity is a little gem.
One thing, - can you please tell me how to do the "Quote" in replying in this forum. I have never been able to work out how you do it !!

RonC.

Edward Troxel · August 9th, 2012, 07:43 AM

Quote:

Originally Posted by Ron Cooper

Thanks for letting me know Herm. Yes, Audacity is a little gem.
One thing, - can you please tell me how to do the "Quote" in replying in this forum. I have never been able to work out how you do it !!

RonC.

If you're quoting the "last" post, you have to click on the "Multi-Quote" button and then reply. The multi-quote button is the farthest one to the right beside the "reply" button.

If you're quoting older posts, you can just click on the "Quote" button.

Ron Cooper · August 18th, 2012, 12:37 AM

Many thanks Edward. I'll know next time. - Sorry for the late reply - I went skiing last week.

RonC.

August 4th, 2012, 08:11 PM	#2
Don Bloom Inner Circle Join Date: Jan 2003 Location: Chicago, IL Posts: 6,609	Re: Getting rid of audio buzz help Kinda sounds like a ground loop. 60mhz. Try the 20 band graphic eq, pull the sliders on either side of the closest to 60 and see what that does. Do it at clip level so you can hear it then once you find it, you can set it at track level or the Vegas mixer. __________________ What do I know? I'm just a video-O-grafer. Don

August 4th, 2012, 09:43 PM	#3
Chris Harding Inner Circle Join Date: Jul 2009 Location: Perth, Western Australia Posts: 8,441	Re: Getting rid of audio buzz help Herm That is definately mains hum and it sounds pretty constant too so it should be easy to kill on the audio plugin. As Don says, the GE should pull it out ...Just open the audio track FX and in the equalizer select Low Shelf tab and set the frequency to say 100hz and then take the gain (next slider) right down to about -12db or more .... you might have to take the frequency a tiny bit higher as there could also be harmonics from the 60hz signal that repeat at 120hz so maybe go to 150 to cover it??? The same advice works brilliantly for wind noise too!! I set the frequency to 400hz and it kills 99% of mic wind noise...useful to know Chris

August 5th, 2012, 09:19 AM	#4
Seth Bloombaum Inner Circle Join Date: Sep 2003 Location: Portland, Oregon Posts: 3,420	Re: Getting rid of audio buzz help Yes, the noise produced when different systems are connected together that don't share a common ground. Any stray electricity will seek to ground, commonly called "ground-loop hum". If recognized at the time of recording, it can usually be completely fixed by using an isolation transformer (The Sescom IL-19 is very popular for this), or, using an xlr barrel adapter that lifts the ground. It's not a simple tone (sine wave) at 60Hz. Meaning, that it has multiple frequencies that are based on the fundamental tone of 60Hz. So, use the narrowest filter you can, and dip at 60, 120, 180, 240Hz etc. Multiple filters may be required, depending how loud the noise is relative to content. __________________ 30 years of pro media production. Vegas user since 1.0. Webcaster since 1997. Freelancer since 2000. College instructor since 2001.

August 7th, 2012, 06:55 AM	#5
Ron Cooper Major Player Join Date: Sep 2005 Location: Sydney, Australia Posts: 481	Re: Getting rid of audio buzz help Herm, I' ve just come across this and as it is a constant even noise it should be quite easy to remove. There is a freebie sound editing program called "Audacity". Download it & open your track in Audacity & make sure there is some clean noise only, - (like the file you sent). then select a few seconds of the noise only, by dragging the hand from left to right, and under the Effect tab select "noise removal" /get noise profile. Then go back & select the whole track or a sample portion of it to try, and then under the effect tab/noise removal (if needed), drag the slider towards "More" - about 80%, and then click "remove noise" This should do the trick, but you may need to experiment a bit for optimum results. - ie. The amount of noise removal on the slider, as while it is quite effective it can produce artifacts in the overall sound if you go too far. Hope this helps, RonC.

August 7th, 2012, 02:37 PM	#6
Magnus Helander Major Player Join Date: Nov 2003 Location: Sweden Posts: 221	Re: Getting rid of audio buzz help On thing that WILL take care of your buzz is Izotope RX iZotope RX - Complete Audio Restoration: Declipping, Declicker, Hum Removal, Denoiser, Spectral Repair, Restore, Remaster, Download There are two versions - not sure which one you will need for the "Remove Hum" and "Spectral Repair". This plug is outstanding and I use it all the time to clean up audio from office environments with airconditioning and other background noise. /m __________________ Magnus Helander, Crossmediageek on G+

August 7th, 2012, 02:57 PM	#7
Gints Klimanis Inner Circle Join Date: Jun 2003 Location: San Jose, CA Posts: 2,222	Re: Getting rid of audio buzz help The methods mentioned before will work. Slightly more manual labor will help eliminate the guesswork. Take a spectrogram (reasonable resolution, such as 2048 pts or more) of preferably at least a second of silence + hum. If you have a low frequency hum, look for a peak at 60 Hz (50 Hz in countries with that A/C frequency) and multiples of that : 120, 180, 240 300 Hz. Use a Notch or a parametric filter set to 60 Hz with a very high Q (20 or higher) (Q is sometimes expressed as Bandwidth, so specify a very small bandwidth) and BOOST by 10 dB. If the hum is twice as loud, you have identified the correct frequency. Then, cut by 10-20 dB or more. Repeat procedure for 120, 180 , etc. Hz, though the amount of cut will be less. Judge by the spectrogram. If you don't have a spectrogram, you can hunt for the frequency with a boosting parametric filter. Just boost by 20 dB and a lower Q/high bandwidth and sweep it around in frequency. This is a hunt or miss procedure and much harder than using a spectrogram. When you find the offender, raise the Q/lower the bandwidth to avoid affecting adjacent frequencies. Finally, replace the boost with a cut.

August 8th, 2012, 06:43 PM	#9
Ron Cooper Major Player Join Date: Sep 2005 Location: Sydney, Australia Posts: 481	Re: Getting rid of audio buzz help Thanks for letting me know Herm. Yes, Audacity is a little gem. One thing, - can you please tell me how to do the "Quote" in replying in this forum. I have never been able to work out how you do it !! RonC.

August 18th, 2012, 12:37 AM	#11
Ron Cooper Major Player Join Date: Sep 2005 Location: Sydney, Australia Posts: 481	Re: Getting rid of audio buzz help Many thanks Edward. I'll know next time. - Sorry for the late reply - I went skiing last week. RonC.