Noise Reduction -- removing backround noise

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welldonep

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Hey good people . . . just a question regarding noise reduction. I've been trying to reduce some zip drive noise on some vocal and acoustic guitar tracks that I recorded on a BR8. I followed the instructions on the following link: http://blake.prohosting.com/~pbbtb/cep20noise.htm

-- this does remove the noise for the most part, but also seems to introduce some unwanted artifacts in the track. Perhaps my question should be . . . do I need an absolutely clear sample of the noise only for this to work effectively? I don't really have a section of the track that is 'just noise', so that's not really possible here. I have since come up with a way to reduce the noise the mic was/is picking up, but of course us 'home recorder's' couldn't possibly reduce 'all' of the noise, so this feature interests me . . . and I still have the older tracks that do have the noise. I have found that the hiss reduction does a better job for what I am dealing with. It seems to reduce the noise w/o disturbing the track itself too much. Anyway, if anyone has any tips on this, and would care to share . . . I would greatly appreciate it.

Thanks, and happy new year to you folks.

Cheers!

Peter
 
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I've been using Cool Edit since nearly last year, and wow, that actually helped me some. I tested it out and it worked pretty well. If you really can't get it to your liking, true to reduce the noise from the source. I don't know what you mean by zip drive though so I don't know what to suggest.
 
I think I know what you mean peter.. It makes the recording sound... sortof digitized in an extemely annoying way..

The only advice I can give you is to get the sample of the noise you are going to remove, and then preview the sample, raising and lowering the noise reduction level until you get it as close as possible... There will still be some noise, and it will still have the digitized craziness, but you should at least be able to find a common ground where to normal ears they are unnoticable.

damn I wish this had a spell check.
 
thanks much for the replies . . . yes, i suppose i need to simply play with it until i remove as much noise as possible w/o affecting the signal too much. i am now taking measures to reduce the noise while recording so i don't have to use such tools. i think that's a better way to go.

thanks again.

-p
 
My way : When you record sumthin, you have a 1-2 second "silent" before the sound recorded. I highlight that part (spot where supposed to be silent but contains noise below -55db), and go Noise Reduction. Effects --> Noise Reduction --> Noise Reduction. Get Profile from Selection. Save it. hit Cancle (or close). Now, highlight the whole wave, and aply the noise reduction based on the profile. It's the best way I do for years...

Jaymz.
 
welldonep said:
i am now taking measures to reduce the noise while recording so i don't have to use such tools. i think that's a better way to go.
Click to expand...

That's the real solution. Noise Reduction is cool for fixing stuff that can't be rerecorded but it's a poor way of producing new material. There will ALWAYS be artifacts. You just hope the artifacts are less distracting than the original noise.
 
James Has It...

In the NR panel, there are a few settings you can change...

The number of samples over to the right (Snapshots In Profile). Default is around 120... you can up that to something larger (say 300 or 500).

When you sample the noise portion of the wave, you will see the noise level on an audio spectrum line. There is a gain line you can choose to change how much reduction you apply to the differring frequencies. Just click on the line to add a bullet point (just like Multi-Track mode). It should start by following the shape of the yellow cluster.

[Noise Reduction Settings] After reading the manual I made these changes:
- Precision Factor: 11
>> Affects amplitude distortions. Seems to work best with odd numbers. Larger is better, but not much effect above 10.
- Smoothing amout: 8
>> Controls the *burbly* noise. I found 8 works well for me.
- Transition Width: 3dB
>> When the noise is not consistent, as in tape flutter, this helps stop the chopping affect as the NR process fades in and out, instead of turning on and off.

Try those settings and see what happens. Check back in the PDF manual (or the book if you have it).

Also, in CEP1.2a & 2.0, the Hiss Reduction algorythms are greatly improved. You might want to try running the HR on a light NR pass.

Good luck!
www.AudioMaverick.com
 
thanks for the extra info 'audiomavrick' . . . it is helpful, and greatly appreciated. i do find the hiss reduction in 2.0 to be pretty good. i'm quite interested in Bias' SoundSoap . . . they don't have a trial version available, but a rep said I could send him a 10 sec clip with some apparent noise and he would clean-it-up with the main preset, and return it to me. it's $80 for the plugin/software . . . which I will gladly pay, if it works as well is i'm hoping. i am always so aware of noises when i'm recording, that sometimes it gets in the way of me enjoying a take, or worse, not being able to keep a good take. anyway, i will try your suggestions.

thank you.

peeeeder
 
thanks

appreciate the posts guys. I'm trying to wow someone right now with noise reduction and hopefully the above modifications will reduce the "tin can" sound high noise reduction usually brings. The person I'm speaking of gave me a couple cd's someone had burned for him from a tape of a speech. There is alot of hiss in it as is to be expected with a mediocre mic/ recording medium. I was doing the standard "select a 'silent' part to get the noise profile" routine and was not messing with any of the other settings. I was trying to compromise between the hiss and the tin can and find a middle ground to work with. When I went to do a vocal compression for speech the hiss was greatly emphasized again. I think these settings are the key to getting a better noise reduction.

thanks again
dlv
 
Some More Things To Try...

If the voice recording is from an orginally mono source, here are a some more things to try...

1. A friend of mine was recovering some 78RPM records, which have a horrible frequency response anyway. He actually over drove the NR until the tinny sound actually went away. I have only been able to repeat this amazing feat one time. But, it may be worth a try.

2. Don't underestimate the power of the parametric equalizer. I have ben able to make up some pretty wild curves to get a decent tonal range. When pushing frequencies so hard, you may not realize how loud the signal is getting. You may start hearing cracks in the audio as the D/A converters start to overdrive. Luckily, there is an attenuation window on this panel. Don't be worried about putting in -12dB.

3. Scientific Filters are also great at eleiminating harmonic issues like this. I have had a good deal of luck with *Chebychev2*. You have to play with the upper frequency and the harmonics (3rd order or so), But, this can also tame that ringing or tinny edge.

4. One of my favorites in a mono voice track is to create a stereo (dual-channel) track and layer it up with Delay Effects that are not too annoying. I susally use the *Full Reverb* section and begin tailoring one of the presets. I'd start with *warm or crisp* stage (can't remember the actual name and I am away from that PC, right now). The idea is to try and build up a believable room sound that is stereo-like. The more width you can get in the room, the less of the center channel you will hear (and that includes some of the hiss).

Numbers 1 & 4 are definately an art in themselves. But, well worth attempting. If you get enough in the image that is acceptable to the ears, the brain will tolerate some of the noise. Remember to edit in at least 24-bit resolution so the math rounding errors occur down below the 16-bit CD threshold. I usually end up at 32-bit (24.8, actually) -- I record with 24-bit DACs.

Let us know how it turns out!
 
peaking

Waves lets me know when I clip with it's little warning lights over the left and right channel. I'll try the alternate nr settings and the eq but usually when eq'ing I really botch things up :)

dlv

yeah...100 posts for me!
 
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