Topic: i need some real help... removing A/C return vent "white noise"?

[justink]

i recorded Jon and Josiah (The Head and The Heart) tonight.  it was a small art space with a noisy air conditioning return suction vent.  when it's off, it sounds amazing.  but when it's on, it's distracting.  i don't know if spectral analysis might fix this or an Izotope plug in? 

i'd appreciate any help. 

please PM me, thanks. 

[Sloan Simpson]

My experience has been that you can't do anything about that without severely damaging the music.

[2manyrocks]

Try a subtle noise gate.

If you have Reaper, you can also try Realfir EQ-check the box "subtract" along with the box next to it "automatically build noise profile."  Playback just a quiet section that has the a/c return noise and nothing else.  Then uncheck Realfir and see if it helps.  The problem is usually the ac is so integrated with the rest of the audio that anything you do is a compromise.  Might help or it might be worse.   

[voltronic]

My experience has been that you can't do anything about that without severely damaging the music.

I've found that to be the case with everything except Izotope RX which can do this kind of noise removal very transparently once you know how to tweak the settings.  The only limiting factor is that you need a dead quiet section of room tone for it to learn as a noise profile.  That's usually not a  problem for me with classical recording, but in a concert with a less than silent audience you're going to be out of luck. 

 

[justink]

My experience has been that you can't do anything about that without severely damaging the music.

I've found that to be the case with everything except Izotope RX which can do this kind of noise removal very transparently once you know how to tweak the settings.  The only limiting factor is that you need a dead quiet section of room tone for it to learn as a noise profile.  That's usually not a  problem for me with classical recording, but in a concert with a less than silent audience you're going to be out of luck.

i might be in luck then because this was a dead quiet room.  i have izotope RX but i can't figure out how to use the denoise tool.  any suggestions?

[voltronic]

Here is my workflow with RX:

1. Find a section of your recording where there is nothing but room tone.  This is critically important.  No clapping, talking, nothing.  Zoom in close and look at the spectrogram really closely to check there are no intermittent background noises.  Select this area.  It doesn't have to be very long, maybe around a second or so.  Too short and RX won't have enough information to build an accurate noise profile.

2. Open the Denoise module and change to the following settings (this is what I have found through lots of trial and error works best for HVAC noise, but your situation may be different):
    Spectral Tab
    Manual
    Reduction Curve (I found this helpful in that the processing more or less leaves alone the treble range where its effects are more audible, but try it with and without.)
    Quality D (processing will take much longer but the results are much better)
    Artifact Control 7.0
    Threshold 0.0
    Reduction 6.0 (the default is 12.0 but I find that causes audible artifacts with the HF range; 6.0 removes most of the background noise but appears to not have the negative effects.  YMMV.)

You might also try the Rumble Reduction preset and tweak settings from there.  That's where I learned to try the Reduction Curve setting, as this preset enables that be default.

3. Click Learn while your noise profile is selected.  If your selection is too short it will tell you.

4. Still with the Denoise module open, move the cursor to a section of your recording and click Preview in the Denoise module.  Listen to see if it's doing what you want.  I keep toggling Bypass to make sure there is nothing undesired happening.  It's also very useful to Preview while selecting Output Noise Only.  When that happens, you should only hear your background noise.  If you hear periodic blips or other phasey sounds, then you have a noise profile that's not good and should start over.

5. Once you're satisfied, make sure Output Noise Only is unchecked.  Then Ctrl+A to select your entire file (or whatever you want to denoise) and click Process.  On my computer it takes about an hour to process a 1 1/2 hour recording with these settings.

6. Listen to the results to check it's how you like it, and then File > Export to save it as a new file.  I always add "RX" or "Denoised" to the file name so I know that has been applied, and I record the exact settings used in a text file.

[bombdiggity]

^ Thanks.  I've run a few classical shows where the white noise from the room is more evident than I'd like.  i thought Izotope might be able to do something with it but had not attempted to try to learn how.  This should save a lot of error and trials. 

I'm thinking there may be a good way in Izotope to try to deal with wind noise from a couple of outdoor things where that was a problem. 

[voltronic]

^ Thanks.  I've run a few classical shows where the white noise from the room is more evident than I'd like.  i thought Izotope might be able to do something with it but had not attempted to try to learn how.  This should save a lot of error and trials. 

I'm thinking there may be a good way in Izotope to try to deal with wind noise from a couple of outdoor things where that was a problem.

It's worth a try, but the above procedure would not work unless the wind was totally constant through the whole recording.  For periodic wind, Spectral Repair might be the module to try.

[bombdiggity]

^ Thanks.  I've run a few classical shows where the white noise from the room is more evident than I'd like.  i thought Izotope might be able to do something with it but had not attempted to try to learn how.  This should save a lot of error and trials. 

I'm thinking there may be a good way in Izotope to try to deal with wind noise from a couple of outdoor things where that was a problem.

It's worth a try, but the above procedure would not work unless the wind was totally constant through the whole recording.  For periodic wind, Spectral Repair might be the module to try.

^ I think that's what someone might have suggested (that you could see the wind noise in the spectral on the low end).  It's not consistent of course so I'm not sure there is an automated or blanket approach short of knocking out or limiting some area of the frequency range. 

[Ultfris101]

I've done a little of this in Audacity which seems to have a similar workflow for noise reduction (ie find a quiet place with just noise, sample it, and subtract it from the problem region) but obviously Izotope RX would have a lot more power.

Are there ever any promos or sales to get it? I see it's $249 ($100 off regular) on the Izotope website right now.

voltronic, thanks a lot for putting sharing your steps.

[justink]

Here is my workflow with RX:

1. Find a section of your recording where there is nothing but room tone.  This is critically important.  No clapping, talking, nothing.  Zoom in close and look at the spectrogram really closely to check there are no intermittent background noises.  Select this area.  It doesn't have to be very long, maybe around a second or so.  Too short and RX won't have enough information to build an accurate noise profile.

2. Open the Denoise module and change to the following settings (this is what I have found through lots of trial and error works best for HVAC noise, but your situation may be different):
    Spectral Tab
    Manual
    Reduction Curve (I found this helpful in that the processing more or less leaves alone the treble range where its effects are more audible, but try it with and without.)
    Quality D (processing will take much longer but the results are much better)
    Artifact Control 7.0
    Threshold 0.0
    Reduction 6.0 (the default is 12.0 but I find that causes audible artifacts with the HF range; 6.0 removes most of the background noise but appears to not have the negative effects.  YMMV.)

You might also try the Rumble Reduction preset and tweak settings from there.  That's where I learned to try the Reduction Curve setting, as this preset enables that be default.

3. Click Learn while your noise profile is selected.  If your selection is too short it will tell you.

4. Still with the Denoise module open, move the cursor to a section of your recording and click Preview in the Denoise module.  Listen to see if it's doing what you want.  I keep toggling Bypass to make sure there is nothing undesired happening.  It's also very useful to Preview while selecting Output Noise Only.  When that happens, you should only hear your background noise.  If you hear periodic blips or other phasey sounds, then you have a noise profile that's not good and should start over.

5. Once you're satisfied, make sure Output Noise Only is unchecked.  Then Ctrl+A to select your entire file (or whatever you want to denoise) and click Process.  On my computer it takes about an hour to process a 1 1/2 hour recording with these settings.

6. Listen to the results to check it's how you like it, and then File > Export to save it as a new file.  I always add "RX" or "Denoised" to the file name so I know that has been applied, and I record the exact settings used in a text file.

REALLY amped to see this. Thank you!  I love learning new things.

[2manyrocks]

I've done a little of this in Audacity which seems to have a similar workflow for noise reduction (ie find a quiet place with just noise, sample it, and subtract it from the problem region) but obviously Izotope RX would have a lot more power.

Are there ever any promos or sales to get it? I see it's $249 ($100 off regular) on the Izotope website right now.

voltronic, thanks a lot for putting sharing your steps.

I haven't seen many deals on RX.  In fact, I bought it, and then they released an upgrade that cost me more shortly afterwards.     Even existing users don't seem to get much of a break on upgrades.  I am sort of the personal view that between the time it takes to "fix" a recording and the cost of RX, it isn't worth it unless you are being paid to fix the recording.