Query on applying Denoiser

[Alastair Traill]

I have been trying to apply the denoiser effect in PPro CS 5.5. I can get the procedure to the stage where a graph of the noise floor is shown at different frequencies. I can adjust the reduction knob through its range of 0 to -20 dB and also adjust the offset knob from -10 to +10 dB. So far any adjustments that I have made using these controls have not produced any audible change.

Is there anything else that I have to do to apply these effects?
The only recordings I have tried were made with an SD 702.

[John Stakes]

Hi Alastair,

Unfortunately Premiere doesn't seem to be as intuitive with its audio controls as it is with video. I've struggled with the controls and spent just as much time researching how to use them. In the end I have nothing useful.

The only tools I use for audio are Compresser, and EQ at times. For any other adjustments I recommend using a dedicated sound program like Soundbooth, which will also save you time.

JS

[Bob Hart]

I second doing the sound fix in a dedicated audio program. I have had good results with Cool Edit Pro which Adobe bought in and renamed Audition.

There is a limit to how much noise you can actually take out before you get a tinkling and bubbling artifact. With Cool Edit Pro, it was possible even to zoom right into the disaplyed waveform and manually if need be, redraw, bad snaps in middle of a mission critical keyword.

There are some features other than noise reduction you can connive and abuse a little to achieve an "apparent" noise reduction as well as a real one. Dynamic effects, delay effects, the thirty channel equaliser and compression/expansion can be used interactively on even a very small shred of sound.

I'm no sound engineer, not even a bootprint, so please do not assign any cred to my comments.

[Bob Hart]

Alistair.

I have never used the Adobe sound function for clean-up so this is wild guesswork on my part.

Is there any chance you have to render the changes you make to the audio in Premiere Pro. With Cool Edit, my recall is that where was an "OK" icon or something similar that had to be clicked on which would apply the effect and save it ( like render ) to a hidden temp file somewhere.

Then when you closed out of the file at the end of a session, you have to save the file. My personal preference was to save my incremental improvements as separate files as the original would be written over.

[Alastair Traill]

Thanks John and Bob,

I have tried another test or two with the denoiser. I used the razor tool to split a long section of “noise” into two and applied the denoiser to just one half. This meant that the treated section immediately followed the untreated section when replayed. I did this to a clip that originated in a camcorder (Panasonic TM 900) and to a clip that originated on an SD 702. I noticed a very small reduction of noise with the treated TM 900 clip and none at all on the treated section from the SD 702. Rendering did not appear to make any audible difference.

Perhaps the problem is that for me, noise is something that I do not want whereas for PPro it is a perfectly good signal?

I will investigate using dedicated sound programs, a quick check has indicated that Sound booth does not work on a Mac.

[Battle Vaughan]

If you are looking for a third party denoiser, I have had good luck with SoundSoap (the low-end version, the pro version is pricey and I have no experience with it). Even the noise reduction in the freeware Audacity works pretty well. Both are available in Mac versions.

[Bart Walczak]

Alastair, if you mean Adobe Soundbooth, it does work on Mac. At least it works on mine :)

Denoiser in Premiere is a poorer equivalent of adaptive remove noise filter in Soundbooth/Audition, and is designed to work in real time. Its application is limited, and usually works best with small amounts of noise. If your noise is very audible, denoiser will not be able to handle it. It determines the basic level of noise automatically, which you then can increase via the offset knob, and attempt to reduce with reduction knob.

It won't reduce significant noise, you need another plugin or application for that.

That said, Audition with its spectral analysis tool is awesome for many noise removal jobs.

[Alastair Traill]

Thanks Battle and thanks again Bart,

Battle, I will investigate Soundsoap and Audacity. Bart, perhaps I have managed to apply Denoiser after all, I got no change when the noise level was high but some effect when there was hardly enough noise to worry about. My experience seems to mirror your comments. Since posting my comment above I have found a source for a Mac version of Soundbooth and I am making enquiries on the pricing of Audition. Incidentally your fix for my PPro launching problem is still working so thanks again for that.

Today I tried the free version of Wavepad on a recording of the Powerful Owl’s “Whoo Whoo” call that was interspersed with the sharp crack calls of a local frog. It was very good at reducing the noise between calls but had some undesirable effects on the calls themselves, the owl sounded as though it was breathing very deeply and the frogs sounded like footsteps on gravel. There is room for improvement.

[Bart Walczak]

Alastair, any noise reduction will influence the signal. It is similar to removing grain/noise from the picture - the quality always suffers. In terms of noise reduction in audio, you get this weird metalic and/or hollow sound, which is a result of removing some frequencies, and leaving others. Noise is most often present in all the frequencies (so-called white noise), and it's impossible to separate it from the signal itself. If you cut only some frequencies, you introduce burbling artifacts. If you cut all, you also cut away the signal.

Since the total amount of perceived noise is proportional to the width of the spectrum, sometimes what also works, especially for wind blowing into the mic, is applying a highpass filter that will cut off the lower frequencies, where usually most noise from the wind resides.

Of course, some algorithms are better than others, but don't expect miracles. It is also good to leave some natural noise, not to have the sound seem to appear from nowhere.