trying to remove some noise: help

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Member Since: Jan 18, 2003

i'm trying to clean up an audio file for someone. it was recorded in a car. it's audio for a documentary film.

problem is, there are like four different kinds of noise. rumbling, a low-ish 'whooshing' sound, another low to midrange wooshing sound, and a high electronic tweeting or something-- a running tone.

what would your procedure be? the track also needs to be louder. notching didn't really work. more gentle roll offs brought things into 'telephone land.'

so i'm not sure how to tackle this.

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Czar of Midi
Administrator
Since: Apr 04, 2002


Oct 11, 2008 08:54 pm

The only tools I use for cleaning up audio are either Sonic Foundry noise reduction or a good parametric with the narrowest Q I can get.

A lot of times you need to go through the file the hard way and pinpoint each instance of an unwanted sound and nail it down that way by applying processing to just that small bit of the file.

Being that there are multiple instances of different sounds that are wanted out the long winded pinpoint method is probably going to be the only option that will yield a good sounding final file.

Member
Since: Jan 18, 2003


Oct 11, 2008 09:19 pm

that's what i tried. i put in several notches, but the whooshing sounds are kind of broad. no matter what i did, there was some noise left, and it was weird because it ended up being narrower noise, so when i ran a limiter, the remaining noise actually became harsh and more obvious

Ne'er ate 'er
Member
Since: Apr 05, 2006


Oct 11, 2008 09:32 pm

Forty, I don't know what you're using -heh-, but if your application has a noise profiling feature as Adobe does, you can select a part of the audio that contains just the noise, get a profile from it, and apply the profile to the entire track. This will remove those noise frequencies.

Bear in mind that it will remove useful program content as well, and you'll have to adjust settings for the best balance between "removing the evil" and "retaining the good."

Member
Since: Jan 18, 2003


Oct 11, 2008 09:43 pm

cubase, but i've never heard of such a thing. anything else you know of that does that? gotta be freeware though

Czar of Midi
Administrator
Since: Apr 04, 2002


Oct 11, 2008 10:00 pm

Try hitting www.kvraudio.com and having a look there. The search tool will probably turn up something.

But some of that stuff is pretty sophisticated and finding it for free might be a challenge.

MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Oct 12, 2008 12:26 am

The most advanced spectral editing and forensic audio programs available are only as good as the program material.

I've never seen (these specialized types of) freeware -- And even most of the "reasonably priced" ones (such as the spectral editor in Sequoia/Samplitude or the Algorithmix spectral units) can only go so far - and only after the engineer really has a handle on using them.

Putting it another way -- Even with the right processing and experience, the best that you can normally hope for is to make what you're trying to accentuate a little better and what you're trying to hide a little more hidden. It's not like you're going to cancel out the noise with a print in a car - That works well for steady-state and nothing else. And broadband noise (which I'm quite sure is what you're dealing with) is terribly difficult to manage.

I do this sort of stuff reasonably often (usually for law enforcement agencies) -- What they want is just to make the speech audible and understandable enough to use as evidence. If someone screwed up a tap and it has 60Hz hum on it, that's easy enough. If there's a lot of hiss and distant background noise, it's usually possible to get something usable - But it's going to sound more like a telephone than anything else. If it's an open mic in a moving car, it can take hours of tweaking with the "good stuff" to get the one line they need for the case. And it'll probably sound like crap - But it'll hold up in court.

Sure - Some recordings can have fairly "miraculous" transformations -- But those are the rare ones.

Member
Since: Jan 18, 2003


Oct 12, 2008 02:01 am

that's what i figured. i thought i could do something until i took a look at the frequencies involved and tried a few cuts. it is broad noise. the part i was listening to was recorded in a closed car. spectral analysis shows a mountain of bass below 100 hz or thereabouts. easy to roll off, but it intrudes a bit into the midrange as well so there is no way to get silence on that completely. without going all 'telephone.' also there are a few different kinds of hums and even a strange running tone in the high frequencies. those are easier to take care of, but they're not the annoying thing.

this is for someone's film. they just didn't record it well and it's not going to be perfectly clear like they want. at least you can hear everyone, though.

Eat Spam before it eats YOU!!!
Member
Since: May 11, 2002


Oct 12, 2008 08:00 am

Yeah, my proceedure would be to ADR it. get the voice people back and have them resay what they said... then try to salvage the ambiance or recreate it. ... I remember watching a 'journey to the south pole' doc where the ADR session was part of the documentary :)

Ne'er ate 'er
Member
Since: Apr 05, 2006


Oct 12, 2008 10:21 am

Quote:
I do this sort of stuff reasonably often (usually for law enforcement agencies)


Haha. I watch a lot of true crime shows, and it always cracks me up when I hear the unintelligible audio (always with subtitles) from suspect interviews. Somewhere in cop training, they should spend five minutes on microphone placement and audio levels.

Not like it's important or anything...

MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Oct 12, 2008 02:21 pm

No doubt - I had to (as an "expert listener") transcribe a recording of some guy in a car trying to purchase "quality time" with 7 and 8 year old girls.

The whole time I was thinking - "I'd have to try sooo hard to MAKE a recording sound this bad..." And how I hoped the guy would rot in hell, etc., etc.

But with all the places in a car to hide a lapel mic - I honestly can't image... It was soooooo bad... So noisy, so distorted -

Eat Spam before it eats YOU!!!
Member
Since: May 11, 2002


Oct 12, 2008 03:37 pm

well some of those mics are really freak'n tiny... I think it was the OG gang bust (in a prison) where they used mics hidden in ID badges given to visitors... they had to give the jury special headphones to be able to make out the audio...otherwise it was just slightly distorted low end static...

MASSIVE Mastering, LLC
Member
Since: Aug 05, 2008


Oct 13, 2008 12:11 am

A lot of that "spy stuff" is just crap - If the PD's would pop for a Countryman element, they could literally stitch it right into a shirt collar and no one would be the wiser.

Heck - the headphone/mic on my iPhone picks up better than that stuff. Crooks have cell phones too - I'd think that it would go unnoticed in most cases.

giv me gear
Member
Since: Jan 29, 2009


Feb 06, 2009 07:03 am

Deleted By Tinstryde

Czar of Midi
Administrator
Since: Apr 04, 2002


Feb 06, 2009 10:28 pm

Um did you look at the date of this thread. Its long over with.

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