Noise reduction (in Adobe Audition)
 

I need to reduce noise in some inteviews and also increase the volume. Its better to reduce noise first and then icrease the volume or vice versa? Maybe it doesnt matter?

Re: Noise reduction (in Adobe Audition)
 

It would probably be best to try it both ways yourself on a sample of your own recording.
Also, probably faster than waiting for an authoritative answer here (if there even is one).

Re: Noise reduction (in Adobe Audition)
 

I've always boosted the level first, going on the belief that you want the NR corrections (e.g. level changes) to be as fine as possible, relative to the overall level. (I suppose, if you extrapolate from that, that it would be even better to convert to 32 bit, but I've never carried things that far.)

I've also found (embarassingly, after I had been using the program for years) that NR seems to work much better if you do it at 96kHz sampling rate... even if the original was 44.1 or 48.

I don't have any quantitative measurements or heavy math to support the above... just my qualitative evaluation when listening to the results. YMMV.

Re: Noise reduction (in Adobe Audition)
 

Never used the NR in Audition but I usually use SCS NR-2.0 as the first process in a chain when needed. If significant NR is desired, two instances NR processing will produce fewer artifacts than one with a high reduction parameter setting, especially with an updated 'noise print' on the second.
Interesting theory Greg, it would have never occurred to me to use a higher sample rate. I'll have to try that. Thanks

Re: Noise reduction (in Adobe Audition)
 

Rick,

I consider that every digital sample is an inaccurate representation of the original analog signal. There is some error between the original and the digitized value. The size of the errors can be reduced by (1.) digitizing at the highest reasonable level, (2.) digitizing with the greatest reasonable sample depth, and (3.) digitizing at the highest reasonable sample rate.

So I try to give the NR algorithm the greatest possible number of bits to work with, within reason. I'm pretty sure that Audition does all internal calculations at 32 bit, so I didn't bother converting the file to that depth. But 96Ksamples/sec did seem to make a difference. That might or might not be noticeable, depending on exactly what tool you're using.

BTW, I agree wholeheartedly: two passes of light NR, with an intermediate noise sample after the first pass, turns out better than one heavy-handed pass. And I try to do the static things first, then the dynamic things last. e.g. if there's a heavy 60Hz hum, I try to remove at least some of that with a fixed notch filter first. Then I take a noise sample and run the dynamic NR second. And if the result isn't quite as quiet as I'd like, I might run a very slight bit of downward expansion as the last pass.

In reality, I should probably be saving these intermediate steps as 32-bit files, because the accumulated errors would be less than when I save each step in 16-bit form. Sigh.....

Re: Noise reduction (in Adobe Audition)
 

I do about the same workflow, HP, LP filtering prior to NR I usually work in Sound Forge Pro and Vegas Pro which use 32 floating bit point.processing. I'm also experimenting with SpectraLayers Pro but the learning curve is steep . I would think that is 32 bit like other SCS apps.
So in my case, do you think re-sampling to 96k, process, and then down-sample back to 48 would not be of much benefit?

Re: Noise reduction (in Adobe Audition)
 

I can't really give a definitive answer to that. It's probably a function of the internal math, and that's going to vary from program to program, and from filter to filter.

I only know that I've gotten better results when I upsampled to 96k before doing the NR. But I suppose the only way to answer that for you, with your software and your material, is to try it. (I feel fairly safe in saying that working at 96k can not make the result any worse.)

And, as I said, I should probably convert the file to 32bits, and save all the intermediate steps at 32 bits, then downsample to 16 bits as the final step. That's because, even though the processing is at 32 bits, if you then save that step as 16 bits you're introducing another "rounding error" in the math. As you have more and more processing steps, and more and more intermediate files, those "rounding errors" will accumulate. I would think this applies to any program and any process.

As I confessed, I haven't done that myself. When I've been doing the really extreme cleaning, it has been on some old material which would never sound really new or pristine, so I thought saving 16-bit files would be adequate. But in theory, and with newer better source material, yeah, I'd probably save everything at 32 bits.

(What's the analogy with images? Wouldn't you do all your work at the highest resolution possible, and then if you need a low-res product, do your final downsizing as the very last step?)

Re: Noise reduction (in Adobe Audition)
 

Myself and most other pro production sound mixers record @ 48/24. No need for dialog @ 96k. My 744 and other location recorders don't offer 32bit as an option anyway.
No to get to far OT, but for video I always render directly from the HD camera files. except for material destined for YouTube, Vimeo or other web streaming, Then it is rendered to an intermediary Avid DNxHD format, then re-render to MP4/H264 in 'Handbrake' ... which seems to be the preferred method for many skilled video folks.. who know a hell of a lot more me, The final picture quality is impressive. This tutorial is from my friends over at the SCS Vegas forum.

Re: Noise reduction (in Adobe Audition)
 

Another great thread with solid advise. I am going to try the multi step process myself next time I need to. Thanks guys.

To the OP. I am not a great audio guy but I can work my way around the fundamentals. What I would say to you is take everything in small steps. Experiment a lot. Sampling your “bad frequencies in Audition and zaping them out of the track will sound terrible if overdone. I have learned good finished audio is a lot like ones taste in food, we are all different. I have worked with one sound guy who knows far more than me about the advanced tools. By the time he is done “sweetening” I never like the result. To him it sounds good, to me it does not sound like the voices we interviewed. I try to do as little as possible with the goal of replicating the real sound in mind.

Steve

Re: Noise reduction (in Adobe Audition)
 

"To him it sounds good, to me it does not sound like the voices we interviewed."
> If you can post a before and after clip, we ('pro' audio folks on this forum) can evaluate your 'sound person's' work. Maybe just a want-to-be with some audio tools. Lots of those types around.

Re: Noise reduction (in Adobe Audition)
 

When I had have to do some serious noise reduction in Cool Edit Pro, Adobe Audition's ancestor, my personal preference has been as Greg Miller suggests, operate in the 96Khz environment :-


Normalise to 95%.

Take a noise sample from a dialogue-free portion of the recording.

Apply the noise reduction to a level where there is reduction but no digital artifacts like tinking or bubbling.

Sometimes I will add a different constant-level background noise of a lower frequency than voices in the hope of masking more extreme noise reduction artifacts if I feel I have to push the noise-reduction too far, a sort of a white noise thing. Often does not work.

If I have two tracks, either stereo or mono copied to a second track, I sometimes invert one of the tracks to see what happens. Sometimes you strike it lucky but there is no science or logic to this.

I use the graphic equaliser in 30 channel to see if I can notch out something undesirable manually in the quieter patches between voices using the zone selection ( highlight ) function.

I try a little compression only. Too much and the noise may "pump".

I select the quiet pieces between the dialogue and lower the audio level. I do this before adding an artificial background or ambience track in a sometime futile effort to mask my errors and any compression pumping.

I try delay and play with the manual settings. Sometimes something annoying may cancel out if you have a mono track, copy it into a second track and apply the delay effects.

I am no expert in this at all so please take notice of other comments over mine.


This old damaged acoustic 78rpm recording represented one of the most extreme challenges I have faced. It remains pretty bad.


The surface damage and wear damage in the groove was rather severe.

There is a mid-frequency artifact which little could be done about. The substrate of the old shellac surfaced disks is reinforced with a woven binder which seems to have the same texture and pattern of old hessian sugarbag material. This pattern is apparent in the surface of the shiny smooth shellac layers which have been glued onto the substrate.

It reproduces as a cyclic and varyingly random low to mid-frequency rise and fall which alters as the stylus migrates to the centre of the record.


This one was less of a challenge but I found it necessary to selectively draw in with the graphic equaliser some of the critical consonents of the words where I was able to and lower levels between some verses to eliminate compression pumping. You will hear where I went a bit too far with delay effects with a reverb on a few strong bits.


I had to draw out a few bad pops manually by stretching the waveform and re-levelling a highlighted very small time period. These digital audio tools are indeed wonderful for damaged recordings. They also enable one to replicate the original equalisation curves the engineers intended before the common RIAA standard was introduced. I have found constant background noise in video recordings a much harder beast to deal with. .

Re: Noise reduction (in Adobe Audition)
 

Adaptive Noise Reduction in Adobe Audition is pretty impressive when working with voice. I usually first run Adaptive Noise Reduction then increase the volume.

Re: Noise reduction (in Adobe Audition)
 

Bob, when I'm cleaning an old mono phono recording, I always record it in stereo (after all, the phono cartridge and preamp are stereo anyway). First I de-click it. Then I listen, comparing channels. Sometimes there is a bad pop/click remaining on one channel only, and I can then select audio from the cleaner channel.

Ultimately, if both channels have similar S/N ratio, I sum both channels to mono, which usually makes the noise level sound lower.

For noise with a steady fixed frequency, I use the parametric instead. First I display the frequency spectrum and get a rough idea where the noise frequencies are located. Let's say I find noise approximately 100 Hz.

Then I open the parametric. Select one filter only. Set Q very high, usually = 50. Set frequency somewhat lower than where the noise is... in this example around 90 Hz. Drag the gain UP to somewhere around +12 to +20. Click "Preview" to start the audio sample playing. Now start increasing the filter frequency, and listen for loudest output. (In this example, it will be somewhere around 100 Hz, but maybe a little higher or lower.) Sweep it up and down until you have the frequency accurately identified. Once you find the frequency with the loudest output, you know your filter is tuned exactly to the noise frequency. Now pull the slider down into the -dB range, and you will hear the noise go away. Don't pull it down more than necessary. Finally, repeat with other offending frequencies.

Sometimes I find this gives better results than the adaptive noise filter, because the parametric doesn't produce any "burbly" and "tinkly" artifacts. You have to use it with caution if you use it within a part of the file containing desired program material, because you will also notch out pgm. matl. with the same frequency.

Re: Noise reduction (in Adobe Audition)
 

Great thread, thanks for this insight. I've been also struggling through figuring out the proper process and have not thought about upsampling first. I'll save this one.

Re: Noise reduction (in Adobe Audition)
 

Greg. - "Record a mono track in stereo". - Yes. I also do this. I have an old AWA gram which has a "mono" setting which somehow seems to clean up a little on its own. The waveform off it is exceptionally weird with the peaks on one side of the centreline about twice as deep as their opposites.

For this and a later electronically controlled turntable, I ended up creating a filter I called de-RIAA and then created other filters for each of the equalisation charts I could find for the various record labels of the times. For what they were, there is a surprising amount of information in those old recordings.

I don't remember seeing "adaptive" noise reduction. It may have been there under another name or function. My latest was Cool Edit Pro v1.5. Parametric equaliser. I shall have to go there. I am not sure if it was in CEP. It may have been that I simply did not dig deep enough. I did use parametric equaliser on a Fostex DMT8 in earlier 78rpm recoveries. To get a full re-requalisation I had to bounce-track it one generation. I was also using and please don't laugh, the dynamic effects of an EM-U ESI-32 sampler with 64Mb of memory for some cleanup. It did quite well but one 3 minute track would take all night to run through and one hoped one got it right.

Re: Noise reduction (in Adobe Audition)
 

You mean with any program material on any disc? If so, that sounds extremely wrong to me. It would almost make me think there's a Class A amplification stage somewhere that is biased wrong, and is not operating in the linear part of the transfer curve.

There's another NR/editing package called Diamond Cut Audio. I believe they're just released v.8, I was a beta tester for v.5 and v.6 a few years ago. As I recall, they have reverse RIAA curves, curves to convert RIAA to some of the other standardized curves, etc.

In fact, the guys developed the software originally so they could clean up some old phono recordings (maybe cylinders; my memory is unclear about that). Then they started to market it. I think they presently sell some of the actual audio recordings, as well as the software.

They actually have a lot of interesting NR tools, some of which Cool Edit didn't have IIRC. Additionally, some of the tools can work in "pass-through" mode, live and in real time. So, for example, if you're broadcasting a live phone call, you can run it through Diamond Cut and clean it up digitally as live audio, on the fly.

I used the program quite a lot for cleaning up some terrible old cassette tapes. But eventually I came back to Cool Edit, because I had learned on that program and could work much faster with their GUI. Still, Diamond Cut has its place, especially for NR, and it's a lot less expensive than Audition.

-- Disclaimer: Although I was a beta tester several years ago, I have no business affiliation with the company.

Re: Noise reduction (in Adobe Audition)
 

The AWA was the first generation of their transistor reproducers and amps, all discreet components and no ICs. Prior to that it was valves ( called tubes in the US ). I think they were still learning the solid state ting then or maybe something has gone off over the years.

Re: Noise reduction (in Adobe Audition)
 

Do you see this same flaw (asymmetrical peaks) on both channels, and on all phono records?

Re: Noise reduction (in Adobe Audition)
 

The waveform is munted in both channels. The old stereogram also used a BSR crystal ( ceramic ) pickup.

Apparently dynamics are best but I personally prefer the "brighter" sound off the ceramic pickups for the older recordings which seems to break through the surface noise a little better. But that is just me. sound is a very subjective thing.

I have also damaged my hearing by being too close to too many angle-grinders and spoiled my hearing through working with HF radio over a period of time which "conditions" one to ignore and filter through noise and static. This is the exact opposite of what an audio engineer is about.

I have an Ortofon pickup with a 78 stylus on an electronic turntable ( which I must get back from the person I loaned it to. )

Re: Noise reduction (in Adobe Audition)
 

My gosh, were there stereophonic ceramic pickups? It's hard for me to remember what technology (or lack thereof) existed 50 years ago. I guess I do recall such a thing, but only in the inexpensive "home quality" phonos, never in anything intended for broadcast or studio use.

However, one reason I asked about "both channels" was because I was pondering whether it's a problem with electronics or with the pickup. It's possible that there is a mechanical problem with the cartridge that is actually causing the stylus to mistrack in such a way that its output (i.e. the input to the preamp) is not symmetrical.

If you're using a pickup that old, and a ceramic one at that, it is probably well past its useful lifetime. Something in the suspension has most likely dried out, and is no longer keeping the stylus (or, actually, the cantilever arm) properly supported and centered.

I hasten to add that playing records with a bad pickup -- which IMHO includes any ceramic pickup -- will greatly accelerate groove wear, not to say damage. I always thought of ceramic pickups as "record eaters" since they require much higher tracking force, which is hell on those very fragile vinyl grooves. Of course if you're playing ratty old shellac discs, perhaps they can better survive the abuse.

Re: Noise reduction (in Adobe Audition)
 

Ceramic or crystal. I may have got it wrong. Basically there are two flat strips agitated by a rubber carrier which supports the stylus. I presume the two very fine centres in each of the strips is the crystal material.

The audio off the dynamic pickups was better for fidelity.

The old shellac-on-bakelite disks suffered from stylus wear as readily as any other. Steel needles would not have been very friendly. In Carnarvon Western Australia, when I was a kid there were still one or two people using mesquite thorns for record needles. They were good for two plays.

Re: Noise reduction (in Adobe Audition)
 

IIRC, ceramic and crystal were the same basic design, just a different piezoelectric material used.

True, the old discs were subject to wear, especially with the acoustic (i.e. non-electric) reproducers. But in that case we're talking a tracking force of several ounces, not a few grams. Surely a '60s era ceramic pickup tracking at ~5 to 10 grams would cause a lot less wear than an acoustic pickup tracking at 10 ounces.

And yes, I have an old crank-up victrola that uses interchangeable steel or cactus stylii. (Actually it's an Edison disc player with an alternate lateral playback head. The head for Edison discs was for vertically modulated grooves, and had a fixed diamond stylus.) There were a few different dimensions of steel stylii, for different playback loudness levels! Some day I should lower the stylus onto a good digital scale, and see just how much tracking force those things exerted... it would undoubtedly be scary.

Re: Noise reduction (in Adobe Audition)
 

Regarding cylinder/roll recordings, there was a guy in Canada I think who was recording from old Edison cylinders using modern stereo pickups but reversing the poles on one channel so that the combination of both channels then detected vertical inputs. His tracking arm was incredibly long but light and balanced so that the arc of movement along the cylinder was as straight as need to be.

Re: Noise reduction (in Adobe Audition)
 

Not even fifty years ago! The crystal/ceramic pickups were still fitted in budget end equipment in the 70s and wary 80s. Garard SP25 and the BSRs with turnover cartridges were very common, and moving magnet cartridges were firmly in the hi-fi end of the product range throughout that time. Hi-fi shops were selling styli for these in the early 90s! Today, technology is obsolete before the guarantee runs out - back then, asking for a new cartridge for twenty year old product was common! I seem to remember selling little in-line pads so old ceramic cartridges could be connected to new amps that didn't have a ceramic input any longer!

Re: Noise reduction (in Adobe Audition)
 

Aargh, you're right, and that brings back terrible memories. We used to call BSR by a name that seemed appropriate, given the [lack of] quality. I will say only that the "B" stood for "Bull" and you can ponder over the rest.

Aside from the difference in gain, IIRC the input for a ceramic cartridge needed different EQ from a magnetic input. One type had output proportional to stylus velocity, the other had output proportional to stylus amplitude. So the "converter" you recall should have had some EQ compensation built in, not just a simple resistive pad.