How to remove humming noise?

Luxo wrote on 2/13/2002, 6:20 PM

I editing a one-hour lecture in Vegas Video 3, and there's a terrible humming noise throughout caused by the camera microphones. Can you audio experts give me some tips on removing it, either with Vegas filters or SF Noise Reduction? Here's a short example of what I'm talking about:

http://www.jerware.org/media/humm.mp3

I'm using Canon XL1s cameras with the built-in shotgun microphone. Has anyone else encoutered this with these cameras?

Many thanks,
Luxo

Comments

EArrigotti wrote on 2/14/2002, 12:49 AM

The best way to remove noise such as humming is to get a good signal beforehand.

My guess is that the audio was very soft and you brought the levels up, therefore bringing up the hum with it.

If that wasn't it, it could have been a ground loop, or A/C hum caused by a poorly grounded electrical outlet.

If you need really clean audio recording, make sure you are getting a good strong (but not overly strong) signal. If you are relying on the camera's built in mic that means you need to get closer to the audio source, either with your camera, or with an external mic. Another route would be to use a separate system to record audio (i.e. a portable DAT recorder or MiniDisc)

I'm sure this isn't what you wanted to hear since you are now in post-production.

So, let me suggest a noise reduction plug-in ala the SF Noise Reduction plug-in. Once you learn how to use it well, it can work MAGIC in removing unwanted noise. However, it ain't cheap!

As a less expensive alternative, but much less effective, use EQ's to remove the frequency where the hum lies (usually down below 100Hz). This will remove some, but not all of the hum.

As the old adage goes, "A stitch in time saves nine". It is wise to learn from this challenge and try to figure out how to avoid the hum in the first place. (he says in a very 'confucious like' tone.)

David_DSS wrote on 2/15/2002, 3:54 AM

Two ways I know of. (There are probably many more.)

1.
Download a free demo copy of Cool Edit 2000 from www.syntrillium.com. The demo copy is fully functional except that it only allows 2 functions to work at any one time. Enable the sound reduction part and you should be able to do what you want. Procedure is to take a sample of noise only, like airconditioner hum, and then use that sample to remove like sounds in the audio.

This is fully legal and is Syntrillium's way to get folks to try Cool Edit 2000 and maybe buy it.

You will have to save your audio file in the .wav format for Cool Edit to work on it. Then import the corrected file back into VV3.

2.
Buy Sonic Foundry's Noise Reduction Plug-In 2.0. This will function as a plug-in within VV3. Currently sells for $279 from Sonic Foundry but you can get it bundled with Sonic Forge 5.0 for $198 from the following link:

http://www.dvdirect.com/Prods/SFD/2024.htm

I can't take credit for coming up with these solutions though. The good people in the following forum get credit for teaching me this when I had a similar problem to solve:

http://www.creativecow.net/cgi-bin/select_forum.cgi?forum=sonicfoundry_vegas

I went with the SF NR 2.0 choice because I liked the idea of being able to use the filter from within VV3 and the bundle with Sonic Forge 5.0 looked like a good deal.

Hope This Helps
David_DSS