Well last time I made a suggestion I ran you down a dead end.
But you may enjoy trying your pair of me-64's using one on subject
and one off. Then try inverting one channel and converting to mono
and see if you get a reduction in background noise.
I don't know how the filtering works from a programming viewpoint to
understand why it defeated your purpose on the test you tried.
I am still trying to understand the cancelling effect I was able to
achieve and doubt if I will. I will try some more simple and
controlled tests. But it does look very worthwhile so far.
good luck
--- In Vicki Powys <> wrote:
> on 11/2/02 11:50 AM, richpeet at wrote:
>
> > Ok I tried this in cool edit. I took a Mono track, converted it to
> > Stereo, inverted one track, and reconverted it to mono. Sure
enough
> > there was no signal left.
>
> Rich and All,
>
> I've just tried inverting a sound track in Peak, then mixing it
with the
> original. Same result as Rich - complete cancellation of the
signal, very
> dramatic! So I thought to make use of this effect by selecting
just the low
> noise out of a recording (using Q10), then inverting that noise,
then mixing
> it back with the original. It has no effect at all. The fact that
I had
> passed the signal through the filter seemed to upset the process
somehow.
> If you wanted to use phase cancellation as a noise reduction method
from the
> files in the computer, how would you do this? I guess it is easier
to use
> band pass filtering, but I'd still like to know how to use phase
> cancellation for noise reduction on processed sounds. Anyone know?
>
> Vicki Powys
> Australia
>
>
>
>
>
> on 11/2/02 11:50 AM, richpeet at wrote:
>
> > Ok I tried this in cool edit. I took a Mono track, converted it to
> > Stereo, inverted one track, and reconverted it to mono. Sure
enough
> > there was no signal left.
> >
> > Now I run a ME 67 long shotgun over my 32" dish. My original
thought
> > was to be able to aim my narrow 32" dish and cya when I overrun
the
> > preamp on a loud recording received by the dish. But I also see
that
> > I can pivot my shotgun because of the way I mounted it and will be
> > able to point it at single source noise problems, invert and
cancel.
> >
> > How far away can I have the diaphrams of the two mics before I
can no
> > longer use this technique? Is 24" to far?
> >
> > --- In Klas Strandberg <>
wrote:
> >> Using a mono parabol, you can have an extra omni outside of it
and
> > connect
> >> it antiphase. By moving it, you can "tune" your filtering to the
> > noise which
> >> is present. The remaining noise is the noise which is reflected
by
> > the
> >> parabol "only".
> >>
> >> Klas.
> >>
> >>
> >>
> >> At 14:21 2002-02-10 +0100, you wrote:
> >>>> Date: Fri, 1 Feb 2002 09:39:46 EST
> >>>> From:
> >>>> Subject: Re: noise filtering 101
> >>>>
> >>>> Jeff,
> >>>>
> >>>> You audio sounds pretty good after being filtered. Here is a
few
> > things I do.
> >>>> When I have recordings with car noise, I first use the FFT
> > filter to do a
> >>>> 85dB rumble cut for anything below 120Hz. That gets rid of wind
> > noise too.
> >>>> When I use noise reduction, I get the profile from the sample,
> > manually
> >>>> select a line just over the green noise signal, and reduce
noise
> > by 80dB. I
> >>>> noticed your settings are at 40dB. I usually keep the noise
> > reduction level
> >>>> slider on the low side. Overdoing noise reduction ruins the
> > quality of the
> >>>> audio, so you might have to play around a little. Cool Edit Pro
> > has a hiss
> >>>> reduction plug-in that seems to work better than noise
> > reduction. There are
> >>>> other noise reduction programs available, such as Algorithmix
> >>>> (http://www.algorithmix.com), that may work better than Cool
> > Edit. I gave up
> >>>> trying to get quality audio anywhere near highways, railroads,
> > and airports,
> >>>> but sometimes that is a luxury that can't be often found.
> >>>>
> >>>> The only thing you can do about faint recording is to either
get
> > closer to
> >>>> your subject or get a preamp for your mic. For noisy
> > environments, getting
> >>>> close to your subject is critical for quality recordings. Did
> > anyone ever
> >>>> think of putting a mic with a long cable on a remote
controlled,
> > camouflaged
> >>>> model boat? Sounds like it could work.
> >>>>
> >>>> Bruce
> >>>>
> >>>
> >>> I experience a continuing growing problem with noise.
> >>> Because of growing population there is always some kind of
> >>> unwanted noise somewhere. You can name them all, plains,
> >>> trains, highways, farmers with machines or a loud radio on
> >>> some populair station. Is it the right way in using all
> >>> kinds of systems afterwards? I experience the same problems
> >>> with overdone or degrading the wanted sound too much by
> >>> cutting too much. With computers today all kinds of
> >>> unbelievable filters can be used. But with severe cutting
> >>> you degrade the wanted sound often too much. I'm wondering
> >>> if it might work when you use a hightech filter between the
> >>> mic and the recorder or by using a shotgun with an out of
> >>> phase random mic for noise canceling. I suppose its not an
> >>> easy task because you have too set the equipment to a
> >>> certain level so your ready for recording instantly. Whats
> >>> your opinion about this?
> >>>
> >>> Joop Nijenhuis
> >>>
> >>>
> >>>
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> >>>
> >>>
> >>>
> >>>
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> >>>
> >>>
> >>>
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> >>
> >> Telinga Microphones, Botarbo,
> >> S-748 96 Tobo, Sweden.
> >> Phone & fax int + 295 310 01
> >> email:
> >>
> >
> >
> >
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> >
> >
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> >
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