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Author Topic: any input about electronic variable acoustic systems  (Read 9350 times)

Aaron J. Percy

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any input about electronic variable acoustic systems
« on: March 22, 2005, 02:54:43 PM »

Hello all, I am interested in these elctronic variable acoustic systems such as the one by LCS and Yamaha.  If anyone has any firsthand info to share that would be great.
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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #1 on: March 23, 2005, 08:17:32 AM »

I have considerable experience with these.

What do you want to know ?
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Aaron J. Percy

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Re: any input about electronic variable acoustic systems
« Reply #2 on: March 23, 2005, 10:19:29 AM »

I am interested in your opinion of the believability of the reverb tail.  I am a recording engineer and am used to having full control at my fingertips, these systems seem like another tool I could use to enhance the experience at my church.  Our current room does not function well for organ and choral music, hand-bells, or as a space for the "rock" band of our contemporary service.  I am interested in possibly designing my own system but I am having a difficult time finding information about the actual setup of the mic/speaker matrix, the formulas used to devise the DSP settings.  I realize that this a big part of the system and would be considered a secret, but any info you might have in regard to this would further my understanding.  Thanks
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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #3 on: March 23, 2005, 02:16:33 PM »

I recommend that you read articles, papers and promo by the folks at Jaffe Holden Acoustics, LARES Associates, SIAP, Yamaha, LCS and 1-2 others I cannot immediately recall but who have pioneered or developed such systems.

In particular the papers by David Greisinger (LARES) are thorough and fascinating.

I know of one contracting firm in the southeastern US who sell their own version of a LCS system (to churches) which is scaled back and they say it works quite well.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Aaron J. Percy

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Re: any input about electronic variable acoustic systems
« Reply #4 on: March 23, 2005, 02:57:19 PM »

Mr. Young,
  Thanks for your help.  I have been reading articles and reviews but was not aware of Jaffe Holden Acoustics, LARES Associates, and SIAP.  I also would be interested in the company you mentioned that is in the contracting firm in the southeastern US you mentioned.  
   Also, I was snooping around and it sounds like you have a cool job!  Thanks again for your help.
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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #5 on: March 23, 2005, 03:36:57 PM »

Where are you located ?

Maybe I can point you to an installed electronic enhancement system.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Ivan Beaver

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Re: any input about electronic variable acoustic systems
« Reply #6 on: March 23, 2005, 07:39:13 PM »

I assume that the firm Tom is talking about is the company I work for dB Audio & Video.  We have (as far as we know) the only portable VRAS system in the world.  We can set it up in a couple of hours.  It takes the VRAS guys a day or two to set up a demo.  The VRAS (LCS) is probably the most realistic system out there.  It does not use time variance in which you can hear the tails moving around if you listen carefully.  The demo we have would make a great recording room.

The knock off we sometimes use (when budget is a problem) is a system that I came up with and works very well.  It can do several things the VRAS cannot.  I am not trying to fool Europian acousticians (just a bunch of Southern Baptists-HAHA).  We have used my system to "copy" the sound of the large sanctuary into the choir room, so the choir feels like they are signing in the main room.

I will say this-there is a learning curve and I am still very much in it (as far as things you should and should not do).  But I am getting better all the time.

One of the biggest things about using a variable rooms system is the room itself.  It needs to be very dry (RT60 around .5-.7 Sec) and totally free of flutter echo.  This is great for speech, but really allows the system to work to its full potential when doing choral or classical or organ music.  It is not cheap to do right, but the results are worth it.

It is my belief that in a few years most venues will be using a system of some sort, when the operators realize that the rooms can have "perfect acoustics" for a variety of types of performances.  Right now the term perfect acoustics applies to one type of performance-what is perfect for speech is lousy for an organ and vice versa.  In the future you will be able to have a conferance during the day and an organ recital at night and every body will be happy, and the owner has now put paying seats in his venue twice in a single day.  When this starts to happen, the "high" price tag will seem small in a very short time period.

Ivan Beaver
dB Audio and Video

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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #7 on: March 23, 2005, 07:52:03 PM »

Yes, Ivan: you are the guys I had in mind.

I agree with all of your points and observations. However, I do not know whether I would find VRAS superior to LARES because I haven't heard VRAS (yet).  LARES is pretty difficult to beat, IMHO.

Guess I need to find a way down to Georgia, and soon. Lots going on with you guys.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Al Zara

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Re: any input about electronic variable acoustic systems
« Reply #8 on: March 23, 2005, 08:09:46 PM »

Hey Tom -
I just read the David Griesinger paper & it was very interesting,
Can something like that be used to undo reverb, or perhaps null reverb?
For instance filling the room or portions of the room with the inverse of what you don't want?
Al -
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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #9 on: March 24, 2005, 04:20:40 AM »

This is somewhat akin to the thread on the LAB section here a PSW titled: "Introducing.... The Cancelling Fader Mode"

Answer: no

In order to cancel (or even reduce) acoustic energy you need to achieve the correct phase response with one source versus the other at all points in space and for all frequencies. This is impossible.  You can position 2 ldspkrs and phase-align them so that at one frequency and at one point in space they cancel. At other frequencies around (and at harmoics of) the center frequency there will be varying degrees of reduction, but not complete cancellation. And there will be points and frequencies where they interfere constructively, becoming louder. Likewise, as you move to another point in space the cancellation (and addition) is incomplete and varies wth position and frequency.

Noise cancellation is achieved to a degree in headphones and in cars (the few that have noise cancelling systems) because the acoustic space is so small and the position of the listener's ears is stationary relative to the noise source and the noise-cancelling transducers.  In cars you are reducing mostly engine and muffler noise, plus some road noise (all low freq's). The outside HF's have been reduced by the cabin walls.  
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Karl P(eterson)

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Re: any input about electronic variable acoustic systems
« Reply #10 on: March 24, 2005, 08:12:28 AM »

While I deeply respect you Tom, is there something about your comment which makes it specific to "anti-reverb" ?

I ask this question because I have seen in commercial use a number of noise masking systems which range from "intelligent" white noise generators (which work pretty damn well adapting to the enviroment). All the way up to full blown maskers which stick halve a dozen meyer-esqe boxes "implanted" into the room, a 25'000 computer and a few nice measurement mics inside and right arround the source as well as a few in the room.

All in all its a 50~60'000 dollar setup and it can only mask up to two sources (I believe) but it was amazingly efective. I saw this system in use in the boardroom-s- of UPS World headquarters a number of years back, and have since seen them in a variety of other lawyers offices and other such places. They have always worked exceedingly well.

Care to clarify?

Karl P
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Tom Young

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Re: any input about electronic variable acoustic systems
« Reply #11 on: March 24, 2005, 08:49:00 AM »

Sure.

We are talking two completely different animals here.

Masking is not cancelling.  

Masking works by introducing random noise which defocuses the ear-brain from hearing what we don't want folks to hear. Typically this is outside of a doctor's or therapist's office where the private conversations would be heard by folks in the waiting room or another office. When we introduce white or pink noise (random noise) at a loud enough level (doeasn't need to be very loud at all, actually) the folks who are exposed to the noise do not hear the conversations, or at least cannot hear them well enough to understand them.  

There is lots going on here.  If it was music we were trying to make "not audible", random noise would not work because music has a rhythmic and repetitve character that we can discern through the noise masking energy.  But in order for us to understand conversation, we need lots of aural cues which are masked by random noise, in this case, and which are also masked by long/late reflections or too-long & loud reverberance in the case of a space with poor acoustics and therefore low intelligibility. Note that you will still faintly detect that human voices are speaking with a noise-masking system or in a low-intelligibility aural experience. But you will not understand most or all of the words being spoken.  This effect is not effected by listener's position because there is no arrival tme relationship between the effect of the random noise and your ears.

Understand why this is not akin to noise cancelling ?

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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Al Zara

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Re: any input about electronic variable acoustic systems
« Reply #12 on: March 24, 2005, 09:02:37 AM »

I think we are comparing apples to oranges.
Like tom said masking is just what it does, it masks.
We were discussing the probobility of introducing the inverse of the room anomolies back in to cancel them out & like explained earlier when dealing with music that is not possible yet...
imagine beeing able to fix an acustical nightmare with out treating the walls.
Maybe in our lifetime we will see this!
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Aaron J. Percy

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my location
« Reply #13 on: March 24, 2005, 09:37:58 AM »

Tom Young wrote on Wed, 23 March 2005 15:36

Where are you located ?

Maybe I can point you to an installed electronic enhancement system.



Baltimore, MD.  This whole thing has become very interesting to me.  I am looking in to the possibility of reducing the standing waves in our current room to make it more ready for an electronic acoustic system.
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Tom Young

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Re: my location
« Reply #14 on: March 24, 2005, 09:52:47 AM »

Well, as we speak there is a LARES system designed for the Air Force band being commissioned in DC. But it's too late for me to try to hit them up for you to go hear/see it.

Sometime in the not too distant future I will hopefully be doing a LARES system in DC myself. Stay in touch and I'll let you know when that happens.

I'll ask my friends at LARES what else they may have in your area.
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Tom Young
Electroacoustic Design Services
Oxford CT
Tel: 203.888.6217
Email: dbspl@earthlink.net
www.dbspl.com

Karl P(eterson)

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Re: any input about electronic variable acoustic systems
« Reply #15 on: March 24, 2005, 10:22:19 AM »

I perfectly understand the differences between masking and canceling, and understand why "noise cans" work how they do with random white noise. Which is the very reason why I mentioned "intelligent" white noise (which really doesn't apply here, I understand) but more importantly the second system (which I was wrong to call a masking system, as it really is a canceling system).

How it works is that it reads (based on the measurement mics) the sound from whatever the noise source is, and generates an off phase signal which is then dsp processed and put out through the different speakers in the room in some proprietary way so as to cancel the noise being emanated from whatever it is that is making the noise.

I do not see how this is different from what they want to do in the "Reduction" thread, although arguably it would be exceedingly difficult to use one for "anti acoustical badness" as you would technically need a system in every single acoustical reflection point.

That is, of course, unless some amazingly complex signal dsp and a distributed system of advanced digital steerable arrays was conceived which could account for every reflection spot in the room, and could fire sound waves at each location (or groups of) in exactly the right time and phase to cancel the waves.

Anyone up for a science project.

Karl "But seriously, I don't get how the system is not a canceling system" P
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Al Zara

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Re: any input about electronic variable acoustic systems
« Reply #16 on: March 24, 2005, 11:54:15 AM »

Have any links for that pruduct... or is it proprietary?
i'd like to check that out.

Sort of like "The cone Of silance 99"
"Missed it by that much"
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Karl P(eterson)

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Re: any input about electronic variable acoustic systems
« Reply #17 on: March 24, 2005, 12:38:39 PM »

I do not remember who's product this is (it was an unbranded system) or even the installer. It has been a good 5 years since I first saw it at UPS, I have heard of it being installed (my father is in a architectural woodworking firm) in a few lawyers offices. I do remember it was highly proprietary (security system on the dsp/computer box, everything unbranded) and that it cost a ton (north of 50 for one source, probably more for 2) There was extensive consideration of the acoustics of the room, and a ton of data being held by the system (dsp) I believe they were measuring and putting in information for a good three or four days.

I can certainly understand why it doesn't make sense that it would work, I probably wouldn't believe it had I not seen it and  believed it.

I believe ups does work with lockheed on certain aspects (technological) of there buisness, is this possibly one of there products?

Karl P
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Brian Bolly

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Re: my location
« Reply #18 on: March 24, 2005, 01:26:46 PM »

There's an old Jaffe ERES system in St John's Episcopal Church in Washington, D.C. right across from the White House.  The install is from around 1990, so I would think its one of the earlier generations of the system.  This was the first one I'd ever knowingly heard and it was pretty cool, considering the natural acoustics of the (small) room.

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Al Zara

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Re: any input about electronic variable acoustic systems
« Reply #19 on: March 24, 2005, 01:49:11 PM »

Thanks for getting back to me!
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Austin Parker

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Re: any input about electronic variable acoustic systems
« Reply #20 on: June 08, 2006, 12:32:39 PM »

Tom Young wrote on Thu, 24 March 2005 08:49

Sure.

We are talking two completely different animals here.

Masking is not cancelling.  

Masking works by introducing random noise which defocuses the ear-brain from hearing what we don't want folks to hear. Typically this is outside of a doctor's or therapist's office where the private conversations would be heard by folks in the waiting room or another office. When we introduce white or pink noise (random noise) at a loud enough level (doeasn't need to be very loud at all, actually) the folks who are exposed to the noise do not hear the conversations, or at least cannot hear them well enough to understand them.  

There is lots going on here.  If it was music we were trying to make "not audible", random noise would not work because music has a rhythmic and repetitve character that we can discern through the noise masking energy.  But in order for us to understand conversation, we need lots of aural cues which are masked by random noise, in this case, and which are also masked by long/late reflections or too-long & loud reverberance in the case of a space with poor acoustics and therefore low intelligibility. Note that you will still faintly detect that human voices are speaking with a noise-masking system or in a low-intelligibility aural experience. But you will not understand most or all of the words being spoken.  This effect is not effected by listener's position because there is no arrival tme relationship between the effect of the random noise and your ears.

Understand why this is not akin to noise cancelling ?




So basically the masking greatly increases the %Alcons? The higher the %ALCONS the harder it is to make out words right? Human hearing depends on consonants to derive and understand speech...  I wonder if there is a way to "dial in" the % alcons?? Am I being too simplistic?
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Austin Parker

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