Re: Re: In celing mics.

["David Buckley" <db@xxxxxxx>]

Soft and hard knee eh?

Compression is a technique whereby you reduce the incoming range of sound.
The knobs on your compressor adjust the way that happens.

There are essentially three groups of settings, and depending onj your
compressor you may have knobs for all or a few (or indeed none!) of these
"settings"

But before piling into the knobs, a bit of background.  Compression is the
art of reducing dynamic range.  And there are a few "styles" (for
want of a
better word) of doing this.  One extreme is called "limiting". 
Doing this,
you prevent your compressed sound ever exceeding a set level.  Below this
set level, the compressor does not change the level, but over this setting
(the threshold) is compresses viciously.  This style is very good for
preserving dynamic range (for that natural sound) whilst preventing
distortion through overload.  This is "hard knee" in action!

The other end is dynamic range reduction over much or all of the dynamic
range spectrum.  So if an input doubles in volume (goes up by 6db), you may
chose to have the output go up by 3db. Or more, or less.

So what knobs may you have

First is threshold.  This adjusts the level below which no compression
takes
place.  Above the threshold, the compressor does "something".  On
compressors without a threshold knob, the input gain has a similar (but not
as flexible) purpose.

You will probably have a ratio control, or switch.  It will probably be
claibrated from 1:1, to 20:1 or higher.  This adjusts how much the
compressor reduces the change in level of the signal.  The higher the
ration, the more extrreme the compression.

You may have zero, one or two time controls.  These adjust the attack and
delay times of the compressor.  The attack ajusts how quickly the
compressor
reacts to an increase in level, and the decay how quickly the compression
"releases" as the input level drops.

Advanced features inlcude side chain processsing, and multiband
compression.
Yoiu may also have expansion or gating facilities.

Not having tried it, I'd suggest that gating is more crtitical than
compression, to silence unwanted pickup of audio.  Compression should
probably be non-agressive, unless the voice recognition system is very
fussy
over input levels.  Too much compression will bring all background noise up
to a similar level to the voice you are trying ot detect.

I have an opinion that by using multiple mics and good DSP processing, room
pickup whilst avoiding extraneous noise should be easy.  The
videoconference
crowd have it licked for their field, and I think similar techniques could
be used for voice control.  But I'm not aware of anyone doing anything
about
it :-)

----- Original Message -----
From: "Eamon O'Gorman" <eamonogorman@xxxxxxx>
Newsgroups: tex.com.ml.ukha_d
Sent: 19 February 2002 18:28
Subject: Re: [ukha_d] Re: In celing mics.


> I've got a similar set up to the one the chap in the U.S is talking
about,
I
> am using the Kustom 6640, which I hope to be able to use the page
input
for
> whole house announcements. As to mounting the mics in the ceiling, I
dont
> see as there is any other real choice,,,,, wall mounting is out of the
> question (wifey would rather rip out my spine than let me chase the
walls).
>
>     I got some tips from Mike at letsautomate, so I am going to try
these
> and see how I get on. If there are any sound engineers out there, can
they
> please explain to me what the hell  "Soft Knee " or
"Hard Knee" means on a
> liimiter/gate for a start, and then explain what the other 14 knobs
annd
> buttons do.....
>
> Regards,
>
> Eamon "Way over my head here" O'Gorman
>
>
> ----- Original Message -----
> From: "psghome2002" <psghome@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Tuesday, February 19, 2002 11:43 AM
> Subject: [ukha_d] Re: In celing mics.
>
>
> > I've not done it yet but am planning on doing the same as you
using
> > Shure intelligent mixer and crown mics. I did get some advice
from a
> > US based guy - I've copied it below. I'd be VERY interested in
your
> > findings, I'm a few weeks away from the whole-house retrofit of
> > lights,power,CAT5 etc and am still undecided whether to go the
full
> > monty with voice recognition.
> >
> > Paul.
> >
> > +++++++++++++++++++++++++++++++++++++++++++++++++++
> >
> > Well whole room voice recognition still has a way to
> > go.  There is just too much background noise to make it
> > 100%.  Using the local phones work much better since it
> > reduces the outside noise such as radios, others
> > talking, etc.
> >
> > I am single so that is not as much a problem for me.
> >
> > I have 4 Crown PZM-11 mikes mounted in the major rooms
> > feeding into a Shure 410 mixer/gate.  Does a pretty good
> > job but there are times where I have to turn down the
> > radio/TV to get understood.  Quieter rooms such as the
> > bedrooms or bathrooms work much better.
> >
> > If I don't want to turn down the volume due to guests, I
> > just pick up a phone, dial # and talk to HAL.
> >
> > One caution, do not put the mikes in the ceiling.  Even
> > Crown states this is not the best place even though it
> > would seem to be.
> >
> > For the house audio, I have a Kustom unit.  Would prefer
> > to have the 6640 but it wasn't out at the time I bought
> > mine.  Would like to upgrade sometime when I find
> > someone that has a need for just a 4X6 instead of a 6X6
> > unit.  The page function would be great to feed HAL into
> > so the responses go to all areas.
> >
> > Has doorbell inputs that could be connected to sensors
> > or X10 devices for notification or alarms.
> >
> > Hope this gives you a little help.  Check out the Feb
> > issue of Home Automation magazine for a more complete
> > list of equipment that I have here.  My home is the
> > Featured home of the month.
> >
> >
> >
> > --
> > Don    K9SOA/4  EM77EX
> >
> > www.k9soa.net
> >
> > Home of "JEANNIE" The House That
> > Listens
> >
> > My voice controlled, automated
> > home that was featured on HGTV's
> > Dream Builder show on home
> > automation
> >
> > Featured Home of the Month
> > Feb 2002 issue
> > Home Automation magazine
> > > Hi Don,
> > >
> > >
> > >
> > >
> > >
> > > I'm just about to start a HA project covering pretty much
> > everything
> > > including Lighting, Security, Heating, Audio etc. I've got a
few
> > > questions I hope you don't mind answering?...
> > >
> > >
> > >
> > > I'm looking at putting in a whole-house open-air microphone
> > system - I
> > > presume you use something like this?
> > >
> > >
> > >
> > > I've tried HAL2000 with some success just using a standard
> > microphone.
> > > How accurate (in terms of recognition accuracy) have you
managed
> > to get
> > > your system? . and how difficult was it to set up?
> > >
> > >
> > >
> > > What equipment do you use?
> > >
> > >
> > >
> > > Many thanks,
> > >
> > >
> > >
> > > Paul Gale.
> > >
> >
> >
> >
> > --- In ukha_d@y..., "Eamon  O'Gorman"
<eamonogorman@e...> wrote:
> > >    I have just started playing with some mics/mixers for
voice
> > control via in ceiling mics. I have a feeling its going to be a
bit
> > of a struggle to get them working reliably, but thats the fun of
> > it....
> > >
> > >   Anyone else tried this, or had any success/failures. I am
using
> > HAL2000 (which has quite good recognition over phone and using
basic
> > pc microphone), but these limiters and gates are looking pretty
> > complex. I've got the wiring right for my first mic, and get some
> > recognition (although not near as good as with my pc mic). If
anyone
> > has any tips I'd appreciate it.
> > >
> > > Thanks,
> > > Eamon
> >
> >
> >
> > For more information: http://www.automatedhome.co.uk
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> >
> >
> >
>
>
>
>
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