Feature Request: Noise Cancelling Filter

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irwazr
Posts: 1
Joined: Sun Nov 17, 2019 1:13 am

Feature Request: Noise Cancelling Filter

Post by irwazr » Sun Nov 17, 2019 1:45 am

Hi all,

Interested to know if there is a filter which performs noise cancelling? Noise cancelling is performed by comparing 2 channels (e.g. Stereo Left and Stereo Right) and keeping only the audio that matches on both. This is used in many places within the media industries, for example a news presenter on TV.

Is there a filter in GoldWave that performs this? If not, how can I go about requesting/suggesting it?

I can think of a possible way to manually work around this in the meantime, but a proper filter would be awesome.

Possible manual method:
1. Record a person talking in front of the stereo mic, and have someone off to the far side of them also talking.
2. Open the recording in GoldWave, and copy and paste the recording to a new file so you have 2 copies of it open (the original and the clone).
3. In your clone copy, invert the right channel (Effect/Invert), and then merge the left and right channels into a single mono channel (Save as/Attributes/choose a mono config).
4. The mono version of the clone recording now contains the noise we want to cancel out of the original recording. So we need to invert it (Effect/Invert).
5. On your original recording, we save it as a mono file, combining the left and right channels (Save as/Attributes/choose a mono config).
6. Copy the full contents of your inverted clone copy into the clipboard (CTRL+A, CTRL+C)
7. Paste the inverted clone exactly over the top of the original copy (CTRL+A, CTRL+V). This merges the inverted clone with the original, and because 1 is the inverse of the other it will cancel out all matching audio, removing the background noise from the original recording, leaving us with only the audio that matched in both mics. This would be in theory the person that spoke in front of the mic.

The results/quality of this would definitely vary according to the situation and position of the mic, but I'm sure you'd agree that even if it works at all it would be a handy and convenient effect to have in GoldWave :)

So does any feature like this exist, or how do I go about requesting/suggesting it?

Thanks.

Tristan
Posts: 329
Joined: Mon Jun 01, 2009 8:20 pm
Location: Southeast Michigan

Re: Feature Request: Noise Cancelling Filter

Post by Tristan » Sun Nov 17, 2019 11:04 am

Are you speaking from professional experience in the broadcast industry? Have you actually used GoldWave? I don't know why people ask, "What does this program do?" when they could easily find that out for themselves. It sounds like you have a lot of ideas, but don't know much about post-production software.

You should at least try out the integrated NR/remastering features in GoldWave and see if they'd fill the bill. Right now, it sounds like you're just daydreaming. Play around with the GW demo for a few hours to get a more realistic idea of the technical problems you're facing. Experiment with the demos of other programs for the same reason.

That said, people involved in serious post-production work use programs like Izotope RX, not GoldWave, to cope with issues like noise. In fact, I think Izotope just released a snazzy new program designed to deal with tricky, post-production dialog issues. Hang out at Gearaslutz if you want to know more.

What I'D like as a GoldWave feature upgrade is 64-bit VST3 support, such as I have in my other audio programs. But I don't think I'll ever see it.
If I can read the manual, so can you.

DougDbug
Posts: 2036
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: Feature Request: Noise Cancelling Filter

Post by DougDbug » Sun Nov 17, 2019 2:03 pm

This is used in many places within the media industries, for example a news presenter on TV.
I've never hear of that and there are a few problems - It will kill the stereo, it assumes that the noise is stereo but the signal is mono, and most mono sources (such as a single announcer) are recorded in mono (from a single microphone).

If you have an analog mono recording on a stereo-compatible format (analog tape or vinyl record) the record/tape noise is usually random and independent on the left & right channels so mixing to mono can reduce the noise by about 3dB.

I have a vinyl noise reduction application (Wave Repair) which allows you to manually select a few milliseconds of left or right channel and copy it to the opposite channel to eliminate a click or pop that only exists in one channel. This often works even with stereo because you can't hear the loss stereo for a few milliseconds. But, it only works on short-duration defects, not with continuous noise.
Interested to know if there is a filter which performs noise cancelling?
GoldWave has a Noise Reduction filter that allows you to feed-in a "noise fingerprint" (a sample of noise only) and it tries to remove sounds that match the noise profile. That works very well with constant low-level background noises but if the noise is bad you can get artifacts (side effects) and the cure can be worse than the disease so it's just something you have to try. It uses FFT to find/match the nature of the noise. Of course it's not simple subtraction because noise is random and the sample won't match the other noise you're trying to remove.

There's a good reason that pro recordings are STILL made in soundproof studios with good equipment, etc.
I can think of a possible way to manually work around.. this in the meantime, but a proper filter would be awesome.

Possible manual method:
GoldWave has a Effect -> Stereo -> Stereo Center which can "isolate and extract" the phantom center. But, it uses FFT so again there can be artifacts.

There is no "simple mathematical" solution for eliminating the sides and keeping the center. There are 4 possibilities -
L (left only)
R (right only)
L+R (mono mix)
L-R (center removal)

I know it seems like there should be a way to combine those to get center-only but no matter how you combine those results, there is not.

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