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Title: minimize noise at 80m from source
Post by: GeorgesAOUN on April 08, 2016, 08:10:36 am
Dears,

Am new in this forum and I need some support for an issue we are currently facing with one of our installations.

We need to install a sound system on a Rooftop (Open air) for a pub/night-club, the problem is that there is a nearby Hotel at 80 meters direct line.

What would be the solution to have a quality sound at the club at a reasonable volume to run the parties without disturbing the hotel visitors?
we have tried several ways of installation but the sound at the hotel is very loud as if we are at the club,

can someone advise about any idea/solution please,

thanks,
Title: Re: minimize noise at 80m from source
Post by: David Allred on April 08, 2016, 09:46:27 am
Absorb, deflect, or both.  A wall is functional, but maybe impractical if a "view" is part of the setting.

Planting trees (evergreens with tight branch formation) as fence takes a while, unless you transplant mature trees.

A second system delayed and aligned to be 180 degs out of phase (or polarity, choose your preferred term that will bring another 10 page discussion).
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 08, 2016, 10:45:50 am
Thank you for your input,

The wall from the hotel direction is made as follows:
1.1m height concrete Wall and on top of it 1.1m height Glass as Fence (Double 8mm security glass).
total height is 2.2m,

does installation the speaker on the ground help?

Can you please elaborate more about the "second system delayed and aligned to be 180 degs out of phase"?
Title: Re: minimize noise at 80m from source
Post by: Scott Carneval on April 08, 2016, 11:44:26 am
Where are your speakers located, and where are they aimed?

Have you considered locating your speakers on the side closest to the hotel, and then aiming them AWAY from the hotel?

2 speakers may not be ideal for 'pub' settings, but should work just fine at night when the venue is functioning as a 'nightclub'. You could run a smaller distributed system at lower volumes for 'pub' scenarios.
Title: Re: minimize noise at 80m from source
Post by: Mac Kerr on April 08, 2016, 12:01:16 pm
A second system delayed and aligned to be 180 degs out of phase (or polarity, choose your preferred term that will bring another 10 page discussion).

And won't work.

Mac
Title: Re: minimize noise at 80m from source
Post by: Keith Broughton on April 08, 2016, 12:57:10 pm
Can you be more specific about exactly what you can hear from the hotel?
Is it all the music, just the bass or both?
Different frequency bands need different solutions.
Title: Re: minimize noise at 80m from source
Post by: Keith Broughton on April 08, 2016, 12:58:34 pm
Can you be more specific about exactly what you can hear from the hotel?
Is it all the music, just the bass or both?
How quiet does it have to be at the hotel to keep them happy?
Different frequency bands need different solutions.
Title: Re: minimize noise at 80m from source
Post by: David Allred on April 08, 2016, 12:58:42 pm
And won't work.

Mac
I thought "one in a million shot" at best.

How about the "Cone of Silence" from GET SMART?
Title: Re: minimize noise at 80m from source
Post by: Ivan Beaver on April 08, 2016, 01:22:42 pm
And won't work.

Mac
Exactly.  You can cancel "some" freq in some direction , but broadband is quite a different problem.
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 09, 2016, 04:39:39 am
Yes,

we tried it,

when we put the speaker on the ground directly near the wall the sound decreases slightly at the hotel, but if we put it 2 meters away from the wall even with the direction is opposite from the hotel the sound raises back again as if you are in the club.
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 09, 2016, 04:46:22 am
We can hear mostly the music,

Will a distributed system using smaller speakers (8 inches) work better than less quantity of bigger ones (12 or 15 inches)?

what should we focus on once selecting the speakers for this task? the DB or the wattage?

thanks,

Title: Re: minimize noise at 80m from source
Post by: Ivan Beaver on April 09, 2016, 11:06:02 am
We can hear mostly the music,

Will a distributed system using smaller speakers (8 inches) work better than less quantity of bigger ones (12 or 15 inches)?

what should we focus on once selecting the speakers for this task? the DB or the wattage?

thanks,
The best way is to use a distributed system of drivers that are less than 1/4" diameter.

That way the sound at the hotel will be COMPLETELY gone.

Now, to be honest, not all of your customers will want to be wearing the headphones----------- ;)

But it is not the size-nor the dB or the wattage of the drivers that will solve your problem.  Unless you just turn it down a lot (the dB level). 
Title: Re: minimize noise at 80m from source
Post by: Keith Broughton on April 09, 2016, 12:11:06 pm
As Ivan says, power and size really doesn't have anything to do with it.
If you have an area filled with sound at a high level, it will leak out to surrounding places.
Your best bet is to use speakers with a lot of forward control  of the sound and face them away from the hotel side.
As for the bass frequencies, you could use a cardioid array to reduce sound to the hotel side.
It won't be perfect but might help.
The problem with sound complaints is that they may not just be "it's too loud" and can often be just "I can hear it and it bugs me 'cause I don't like the music"
Tough nut to crack.
Title: Re: minimize noise at 80m from source
Post by: Ivan Beaver on April 09, 2016, 12:42:26 pm

Your best bet is to use speakers with a lot of forward control  of the sound and face them away from the hotel side.
As for the bass frequencies, you could use a cardioid array to reduce sound to the hotel side.

And the only way to do that is with LARGE horns. 

A very common misconception is that line arrays do this.  Actually they are HORRIBLE at providing front to rear control.  They can provide vertical control (with a number of strong lobes still coming off at various angles), but if you look at REAL data/measurements/balloons, you will see almost as much energy coming off of the BACKSIDE as you do the front (except at the highest freq).

When inside a room, this can causes lot of additional reflected energy to bounce around.  And outside, it does nothing to reduce the energy behind the array.

A large horn-with all of the devices mounted on it-so they are affecting the pattern, WILL be quieter behind it than in front of it.  In many cases MUCH quieter.

As usual, it depends on the size and the pattern of the horn.

For a given size-a wider pattern horn will control down lower.

So if you combine a large horn, with directional subs, the energy behind the system could be much less.

Even putting "barn doors" on regular cabinets can help to reduce the energy behind them.  However-if these are not part of the design, the sound out front could be compromised.  But that might be OK as long as the energy behind is reduced.
Title: Re: minimize noise at 80m from source
Post by: Keith Broughton on April 09, 2016, 02:00:22 pm
the sound out front could be compromised. 
It's a DJ...some compromise won't be noticed  ;D
Title: Re: minimize noise at 80m from source
Post by: David Buckley on April 09, 2016, 06:38:55 pm
Can you put the speakers above the dancefloor facing down?
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 11, 2016, 03:31:31 am
Thank you for your feedback,

can you please advise about the Horns, since it's new to us.
Is there any link or pictures on the web to check how it is installed and how it works so we can make a test.

thank you for your continuous support,
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 11, 2016, 03:37:23 am
Can you put the speakers above the dancefloor facing down?

yes we have a bridge at 5 meters height above the dancefloor, we tried installing 2 x 12 inch 'Betta three' speakers facing down, it didn't help.
Title: Re: minimize noise at 80m from source
Post by: Lee Buckalew on April 11, 2016, 06:12:41 am
And the only way to do that is with LARGE horns.

Not the only way.
Numerical optimization with MLA will create the wanted coverage at the listening plain and minimize spill outside of that by creating areas of non-audience where acoustic energy is cancelled (typical target for reduction is 20dB/SPL below mix position goal).  You can also create an area of greater reduction (hard avoid, typically targeted at 30dB/SPL below the mix position SPL target). 
Sub-bass directivity can be accomplished by utilizing either cardioid or combination cardioid, broadside array layouts as Keith suggested.  Obviously that directivity will not stop reflections from the building itself.

Overall control ability for non-audience and hard avoid depends on the number of band specific elements being optimized.

I have a feeling that this would be out of the budget range for this project but I could be wrong.

Lee
Title: Re: minimize noise at 80m from source
Post by: Ivan Beaver on April 11, 2016, 12:58:14 pm
Not the only way.
Numerical optimization with MLA will create the wanted coverage at the listening plain and minimize spill outside of that by creating areas of non-audience where acoustic energy is cancelled (typical target for reduction is 20dB/SPL below mix position goal).  You can also create an area of greater reduction (hard avoid, typically targeted at 30dB/SPL below the mix position SPL target). 
Sub-bass directivity can be accomplished by utilizing either cardioid or combination cardioid, broadside array layouts as Keith suggested.  Obviously that directivity will not stop reflections from the building itself.

Overall control ability for non-audience and hard avoid depends on the number of band specific elements being optimized.

I have a feeling that this would be out of the budget range for this project but I could be wrong.

Lee
This might be of interest

http://www.sseaudiogroup.com/write/PDF%20Library/PDF%20Reports/VC-SSE-MLA-K1-TEST.pdf
Title: Re: minimize noise at 80m from source
Post by: David Allred on April 11, 2016, 01:41:04 pm
This might be of interest

http://www.sseaudiogroup.com/write/PDF%20Library/PDF%20Reports/VC-SSE-MLA-K1-TEST.pdf

So the results of the test are that large fans should be used to blow the sound away from the hotel?
Title: Re: minimize noise at 80m from source
Post by: Lee Buckalew on April 11, 2016, 03:11:15 pm
This might be of interest

http://www.sseaudiogroup.com/write/PDF%20Library/PDF%20Reports/VC-SSE-MLA-K1-TEST.pdf

So from these tests, both K1 and MLA would provide very significant reductions at 50m behind the arrays.
The tests show a 105dB/SPL-A at 50m in front, on axis and a 79 or 80 dB/SPL level 50m behind the arrays.

Estimates would be nearly a 40dB/SPL reduction.

Lee
Title: Re: minimize noise at 80m from source
Post by: lindsay Dean on April 11, 2016, 03:19:58 pm
@?
Title: Re: minimize noise at 80m from source
Post by: Lee Buckalew on April 11, 2016, 03:31:14 pm
@?

If that was a reply to me I mean a nearly 40 dB/SPL-A reduction from an estimated level at the arrays to a point 50m behind the arrays.  I only saw a normalized level at 50m in front of the arrays and a level at 50m behind but no level at the arrays themselves, hence the "estimated".


Edit to add on axis performance notes.

If we look at on axis performance vs. theoretical levels we see that both systems performed within a + or - window of 0.75dB/SPL-A weighted of each other and both dropped significantly below the theoretical SPL level at distances beyond their targets when considering both distance and air absorption.


Lee
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 12, 2016, 03:11:06 am
So the results of the test are that large fans should be used to blow the sound away from the hotel?

So you mean we should install the speakers in the opposite direction of the hotel and also install large fans behind it?
Title: minimize noise at 80m from source
Post by: Scott Carneval on April 12, 2016, 07:40:04 am
So you mean we should install the speakers in the opposite direction of the hotel

Yes

Quote
and also install large fans behind it?

No. But if you do this please take pictures and/or video and post here.
Title: Re: minimize noise at 80m from source
Post by: David Allred on April 12, 2016, 07:56:07 am
So you mean we should install the speakers in the opposite direction of the hotel and also install large fans behind it?

Fans sufficient to accomplish the task would then become the noise problem for the hotel and be a major safety hazard.   ;)
Title: Re: minimize noise at 80m from source
Post by: g'bye, Dick Rees on April 12, 2016, 09:56:21 am
Georges...

No matter what you do in such a situation you WILL get complaints due to the nature of intelligible /coherent sound vs diffuse/broadband sound such as white noise.  Pulsing, rhythmic sound such as music will be perceived as "loud" simply because the nature of the rhythm attracts the ear, EVEN AT AN AVERAGE SPL MUCH LESS THAN WHITE NOISE.

The only real recourse after you have done your best to tame your levels as much as possible is to work with the neighbors in good faith and within any existing statutes governing sound levels and times of operations.

In the end, such issues fall on subjective perceptions rather than objective, measurable criteria.  It's more diplomacy than anything else.

See if you can give the hotel guests passes/discounts/coupons so the hotel can become an ally rather than an adversary.
Title: Re: minimize noise at 80m from source
Post by: David Allred on April 12, 2016, 01:02:20 pm

See if you can give the hotel guests passes/discounts/coupons so the hotel can become an ally rather than an adversary.

Good comment.  Honey vs. vinegar
Title: Re: minimize noise at 80m from source
Post by: lindsay Dean on April 12, 2016, 02:12:21 pm
    white noise directed toward the hotel
 would help, depending the level needed and on whether they prefer it over music.
probably would get "air noise" complaints..............oh well
Title: Re: minimize noise at 80m from source
Post by: g'bye, Dick Rees on April 12, 2016, 02:50:51 pm
    white noise directed toward the hotel
 would help, depending the level needed and on whether they prefer it over music.
probably would get "air noise" complaints..............oh well

Don't be silly.
Title: Re: minimize noise at 80m from source
Post by: Len Zenith Jr on April 12, 2016, 04:17:13 pm
There is always di-pole speakers (driver mounted on an open baffle) which will have a null along the plane of the baffle. Inefficient but excellent at cancellations along the plane.

Another option would be get the sound source as close to the audience as possible, as in right on the table:

https://www.cinemarsolutions.com/sportsbar.sportsselect.php (https://www.cinemarsolutions.com/sportsbar.sportsselect.php)
http://www.bestbuy.com/site/bose-soundlink-color-bluetooth-speaker-blue/7902901.p?id=1219300342785&skuId=7902901 (http://www.bestbuy.com/site/bose-soundlink-color-bluetooth-speaker-blue/7902901.p?id=1219300342785&skuId=7902901)

The bose devices actually sound pretty good for what they are.
Title: Re: minimize noise at 80m from source
Post by: Keith Broughton on April 12, 2016, 05:55:27 pm
I'm with Dick on this one.
You need to talk to the hotel people and find out exactly what, and when, the problem is and try to come up with a suitable compromise.
Sometimes just showing you are willing to address the issue can go a long way to smoothing over the problem.
Title: Re: minimize noise at 80m from source
Post by: GeorgesAOUN on April 15, 2016, 03:47:58 am
Ok then,

Thank you all for your support,

Have a good day,
Title: Re: minimize noise at 80m from source
Post by: Mike Sokol on April 15, 2016, 07:08:41 am
Pulsing, rhythmic sound such as music will be perceived as "loud" simply because the nature of the rhythm attracts the ear, EVEN AT AN AVERAGE SPL MUCH LESS THAN WHITE NOISE.

Not suggesting this as a solution, but when I was in a loud garage band practicing in a small town, we got all kinds of noise complaints until we ran a lawnmower in the backyard while we practiced. I also made a recording of a clothes dryer running and looped it on a 90 minute cassette tape played a boom box outside of the our kid's rooms when they were babies. That way they wouldn't wake up every time there were any noises in the house or a truck backfired in the street. Masking noise can be your friend.
Title: Re: minimize noise at 80m from source
Post by: g'bye, Dick Rees on April 15, 2016, 09:10:37 am
Not suggesting this as a solution, but when I was in a loud garage band practicing in a small town, we got all kinds of noise complaints until we ran a lawnmower in the backyard while we practiced. I also made a recording of a clothes dryer running and looped it on a 90 minute cassette tape played a boom box outside of the our kid's rooms when they were babies. That way they wouldn't wake up every time there were any noises in the house or a truck backfired in the street. Masking noise can be your friend.

One way to emulate a "whiter", more diffuse sound would be speakers at the individual tables a la the diner booth juke boxes of the 1950's.  This would require no amps on stage and E-drums, though.

A more likely solution would be down-firing speakers on an overhead grid system, but still the no amps, E-drums policy.