Audacity Forum

I have just recorded a side of an LP and from the tutorial about noise removal, I got the noise profile from the very start and then removed it over the whole recording.

How do I know for sure that Audacity is just removing the noise and not any of the recorded music? The same applies to Click removal

Should I also just leave the arrow on the 'less - more' bar in the middle?

I'm sure that I read somewhere to perform one task before the other. Is that right and if so do I do noise removal then click removal or the other way round?

Noise Removal takes care of the low background noise and Click and Pop removes really loud sounds--sounds much louder than the music.

I would get rid of the clicks first and then apply Noise Removal for the groove noise that's left. Click removal uses the overall personality of the sound to figure out where the clicks are, if the music is different from the original, the tool may not behave properly.

There is no way to know whether "too much noise" has been removed. I will tell you Audacity has not got the best control over amount of reduction. Most people use either all the way down or almost all the way down. The slider was badly designed. I do noise removal in a different program.

Koz

If you're just recording and cleaning LPs, I highly recommend using Audacity 1.3.3. It's got a much nicer Noise Removal, and an Effect called Repair which can be used on individual clicks and pops and comes highly recommend by several other board members (I don't do this kind of work, so I can't say for sure).

But there is a way to see just what Audacity's Noise Removal has removed.

1) Open up a noisy track. Copy / Paste a second copy of it into a new track. You should have two identical tracks now.

2) Perform the Noise Removal on ONE of them as you would normally.

3) Invert ONE of the tracks (it shouldn't matter which one).

4) Highlight both ([ctrl]+a) and click Project -> Quick Mix (or Tracks -> Mix and Render in 1.3.3). You will be left with a single clip containing only the sounds removed from the original track. When I do this it sounds like high frequency junk and very faint unintelligible vocal sounds (used on a poorly recorded speech track).

I am interested in video work with a consumer camera which is not brilliant for locking out the sound of background motor noise - some are better than others - I would like to remove as much of this noise as possible either with audacity or with a plug in or with other software. Anyone have any experience of this problem and its alleviation.

dongle99 wrote:I am interested in video work with a consumer camera which is not brilliant for locking out the sound of background motor noise - some are better than others - I would like to remove as much of this noise as possible either with audacity or with a plug in or with other software. Anyone have any experience of this problem and its alleviation.

There is only a limited amount that you can do (with ANY software).

If the "background motor noise" is VERY background (ie a distant, quiet, regular rumble), then you may be able to reduce it a little with the "Noise Removal" effect - however you will still get some of the noise breaking through, plus some strange bubbly artifacts.

The problem is that traffic noise is broad-band (has a wide range of high and low frequencies) and erratic, so there is no consistent "profile" for a computer program to lock onto.

If it is speech that you are recording, there's not really much you can do but limit the frequency range. With speech, there is little below about 200 Hz, or above 12 kHz, so you can use Eq. to roll off the very low and very high frequencies. If there is a lot of background noise, you can make it more intelligible by rolling off from below 1 kHz, and above 4 kHz, but it will start to sound like an old telephone.

You will see on TV news, that reporters in the street often use special microphones that are held right up against the mouth. This is to maximise the voice signal and minimise the background noise, and that is the most effective approach to take.

And one other note. Even the high-end noise removal programs fall on their face if the noise is changing. The Noise Removal Tool takes a "fingerprint" of the room without anyone talking and then tries to subtract those noises from the show. If the noise changes at all (a car speed up), you need to take another fingerprint. Trying to get rid of live traffic noise is pretty much impossible.

As above, solve at the performance level, not post.

Koz