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Subject:Noise Reduction
Posted by: Widetrack
Date:4/28/2004 10:42:43 AM

I'm trying to remove air conditioner noise from a talking head narraton. Using NR 1.0 works, but the voice ends up with a hollow-sounding, almost flanging quality.

Are there any good ways to prevent or fix this?

Subject:RE: Noise Reduction
Reply by: rraud
Date:4/28/2004 11:39:34 AM

With excessive amounts of noise reduction, this is a side effect.
Try running NR two or possibly three times with less reduction, instead of processing once, using a lot.
Ex.: Process twice @ -15dB of NR instead of once @ -30dB.
Get an accurate "noise print" each time. ie: 10 miliseconds or so of just the A/C noise/room tone.

Subject:RE: Noise Reduction
Reply by: Widetrack
Date:4/28/2004 4:58:41 PM

Thanks, I'll try that. But I wonder if you intended to use realistic numbers. I used about 13-15 dB reduction once and got this artifact.
Subject:RE: Noise Reduction
Reply by: farss
Date:4/29/2004 7:26:03 AM

Works fine for me with even 20dB in one pass. Maybe your problem is not getting a clean sample. You need to check that the noise sample contains nothing but the unwanted noise. Even the slightest amount of anything else can give nasty effects. You can also look at the noise profile to see what is going to be removed, that can give you a pointer to how things will turn out.
Subject:RE: Noise Reduction
Reply by: Widetrack
Date:4/29/2004 1:15:45 PM

Farss:

You said:
You can also look at the noise profile to see what is going to be removed, that can give you a pointer to how things will turn out.

I've never figured out what good the noise profile does. How do I interpret it?

I'll also double check to see if my sample is contaminated.
Subject:RE: Noise Reduction
Reply by: keether
Date:4/29/2004 1:36:26 PM

I don't know what air-conditioner noise would sound like, other than what I hear in normal life.

But when taking noise away from a music track, you can listen to the "removed" sound and if any music is in it, you've possibly taken too much away.
Subject:RE: Noise Reduction
Reply by: Big_Faced_Boy
Date:4/30/2004 6:24:17 PM

Try the different modes and increase the window size for long samples. This particularly helps reduce the flanging in mode 0. Try listening to the residual output and play with the other settings, particularly the top two sliders.

BFB
Subject:New!!!
Reply by: somhairle
Date:5/2/2004 7:22:27 PM

How do I actually remove background noise from an audio file? it was originally recorded on a digital camera @ 22,050Hz / 8Bits / Mono.

obviously i want to keep clear dialogue (as much as possible!!)
Subject:RE: New!!!
Reply by: MJhig
Date:5/2/2004 8:47:46 PM

This is too vague. Audio is far from; "take steps 1, 2 and 3 and everything will be all better".

The OP in this thread has NR 1 which is limited, no Mode 3 etc.

Let's start with;

Do you have Noise Reduction and what version?

MJ

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