Identifying offending noise by using spectral frequency display
 

Hi,

I have a recording where there is a bang happening during the interview. I'm trying to remove it using Izotope RX but I'm having a hard time isolating the offending sound. Here is a screenshot of the spectral frequency display and I'm attaching that section of the audio that has that bang sound. Can someone tell me where on the spectral frequency display that sound is? Do you think it's possible to remove this sound? I have this banging happening in 3 sections of the recording. It would be nice to be able to remove it

THANK YOU!

Re: Identifying offending noise by using spectral frequency display
 

The bang overlaps speech on a spectrogram here, so it's not easy to get rid of it. You'll need to use Deconstruct instead of Spectral Repair.

Re: Identifying offending noise by using spectral frequency display
 

Hi Kathy

Do you have a bit longer clip so we could get a better idea of the pre and post "bang" content - maybe 10 - 15 seconds or so?

Re: Identifying offending noise by using spectral frequency display
 

Hi Jim,

Here is the file with more content. Is this enough?

Re: Identifying offending noise by using spectral frequency display
 

Thanks Alexey, I don't seem to have Deconstruct in my version of RX, is it part of the Advanced version?

Re: Identifying offending noise by using spectral frequency display
 

Yes, it's Advanced-only.

Re: Identifying offending noise by using spectral frequency display
 

:(

Thank you for your help though. May I ask how do you actually know that that's where the bang is on the spectrogram?

Re: Identifying offending noise by using spectral frequency display
 

I have listened to a few selections in your file. My first suspicion was the vertical line before my selection, but it turned out to be letter 'k'. Finally I have arrived at the correct selection.

When you have experience with audio, you can estimate the frequency content of any sound. In your case, it's a noise burst at lows and mids. And it has a considerable decay, due to reverberation.

Re: Identifying offending noise by using spectral frequency display
 

Thank you. I also thought it was the vertical line but when I isolated it I learned it wasn't it. Thank you

Re: Identifying offending noise by using spectral frequency display
 

I downloaded the trial of the Advanced version of RX. I won't be able to save it anyway but I thought I would try to see what I could possible achieve but I'm not able to get a good result either. Makes me think it's not possible to remove this. I wish I could at least lessen it. Anyone has any other ideas?

Re: Identifying offending noise by using spectral frequency display
 

Can you select the speech harmonics in Izotope? That's the procedure in SpectralLayers.

Re: Identifying offending noise by using spectral frequency display
 

A quick and dirty try with noise reduction in (freeware) Audacity makes some improvement, imperfect but less noticeable. The sound seems to mostly fall between "the" and "com" and between "com" and "part" and by taking small slices of the intervening space and doing a 6 to 12 db reduction on those samples (three) you can get what might pass as a momentary blip that most people would disregard, rather than a burst of hiss that does stand out. Then, applying the sample to the "com" phrase removes some of the underlying hiss without destroying the vocal.
Also reducing the pause after "-mentalization" takes care of the rest. You do it in pieces, a little at a time....

Fortunately this sound falls largely in a pause in the narration, making the reduction samples possible. Now, if the sound is the same in the other places, it might be possible to use the samples from the first situation and apply them (one at a time, obviously) to the others, hopefully then reducing the sound and not affecting the speech too much. (If the second and third sounds overlap the speech, you'd not want to sample there because the speech would be part of the reduction sample.)

Re: Identifying offending noise by using spectral frequency display
 

I don't think so. At least I don't know how

Re: Identifying offending noise by using spectral frequency display
 

Thanks, I did the same thing you described but in Izotope Rx and managed to make it less noticeable.

Re: Identifying offending noise by using spectral frequency display
 

Here's what I came up with just for the record

Re: Identifying offending noise by using spectral frequency display
 

Nice one, Jim, want to share how you did it? :)

Re: Identifying offending noise by using spectral frequency display
 

Pretty much the way Alexy suggested - using the Deconstruct module in Izotope 5 Advanced.

Honestly I had never used Deconstruct before so I thought it would be a good chance to learn it and I started working in my typical scientific way - in other words playing around with parameters with no clear idea of what they meant, just tweaking and listening to see if things got better or worse. Made a mess and had to start over half a dozen times (or more) but I kept at it and little by little figured it out and arrived at settings that seem to have done the trick

Now comes the hard part - working back from the result to an effective process that will get me there more efficiently.

Re: Identifying offending noise by using spectral frequency display
 

Nice work, nice tool, also. Worth the considerable investment, I expect! Thanks for sharing.

Re: Identifying offending noise by using spectral frequency display
 

I think Izotope has been one of my most used packages for the last few years. The only thing I record is classical concerts and it's been enormously helpful in getting out the inevitable coughs and sneezes and whatever. I had a string quartet recording a few years back where the cellist bumped the cello against a chair - horrible sound. I was able to repair it with Izotope. Had another one where one of the French Horns came in early and I was able to hide it pretty well.

I was pleasantly surprised at how well Deconstruct worked - in fact I ran it over the whole clip and I think it cleaned up a lot. I might go back and see how it does with the bumped cello. I'm definitely a fan of the program even though it is a bit pricey.

Re: Identifying offending noise by using spectral frequency display
 

The bump is gone but I feel like the vocal is way too distorted in this case. Hearing the distortion of the voice I think I would opt out for something in between minimizing the bump and not completely distorting the voice. Thanks!

Re: Identifying offending noise by using spectral frequency display
 

With Deconstruct, you can always mix the dry and wet signals to your taste: they are phase-coherent.

Re: Identifying offending noise by using spectral frequency display
 

Sorry to chime in so late, I've been out of town and away from my audio machine for quite a while.

Here's a quick fix. I could probably refine this a bit if necessary. How does this sound to you?

Re: Identifying offending noise by using spectral frequency display
 

Greg, that sounds great. What did you use?

Re: Identifying offending noise by using spectral frequency display
 

Kathy, I'm glad that sounds OK to you.

I used several passes of [adaptive] noise reduction, after choosing the areas for the noise samples very carefully.

In general, I convert the sampling frequency to 96 kHz before processing. That provides more data points for the math to work its magic. (And in this case I converted it to mono, since both channels were identical.)

Then I slow down the playback frequency to 48 or even 32 kHz, so I can hear very precisely when various sounds start and stop. That allows me to accurately choose what parts of the file to use for my noise samples. I don't want to inadvertently include some voice in the noise sample.

In the case of your file, I heard obvious differences in the noise characteristics from one spot to another, so I processed each syllable separately, and then blended all the parts back together by cross-fading them.

I still hear some NR artifacts, especially when listening on headphones. And the timbre of the NRed voice is different from the timbre of the raw voice. (No easy way to avoid that, given the random frequency distribution of the "bang.") But it lasts less than 1/2 second, so hopefully most people won't notice it (especially if they're not looking for it).

As I said, it might be possible to make it a bit better with a lot more work. I posted the "15 minute" version just as an illustration.

Re: Identifying offending noise by using spectral frequency display
 

That's awesome Greg! Thank you for the explanation. Yes I do hear some NR artifacts too when I listen on headphones but that's so minor that with the music in the background you wouldn't even notice. A question for you. Did you use Izotope RX or something else?

Re: Identifying offending noise by using spectral frequency display
 

I used Adaptive Noise Reduction in Audition.

Re: Identifying offending noise by using spectral frequency display
 

Kathy,

Try this version. Maybe you can use this.

(Oops ... I left the sampling frequency at 96 kHz. You can easily downsample it to 48.)

Re: Identifying offending noise by using spectral frequency display
 

This may be too simple to work, but are any of the words/phrases that have the noise repeated noise free elsewhere in the audio?. If so perhaps they could be copied and then pasted as replacements for the noisy spots where other processing does not work well.

Re: Identifying offending noise by using spectral frequency display
 

In my experience, it would be rare for the "replacement" words to be the right pitch, inflection, and pacing. (Of course if you had another take of the same script, that would improve the probability.) There's a slim chance you might get away with it.

Re: Identifying offending noise by using spectral frequency display
 

"words/phrases that have the noise repeated"
- I do that frequently and is SOP for dialog editors. Unfortunately documentary type programs rarely have a word or line multiple times in the same tone, but occasionally you get lucky.

Re: Identifying offending noise by using spectral frequency display
 

That was the first thing I checked.