Active noise control- the stuff in electronic mufflers

[jacques b gros]

We have a nice range in Rio, copy of Sidney's. As it happens, the copy was sloppy, and there is no acoustic treatment on the thing. When 8 shooters are in Rapid Fire conversation stops all over until the blast is over.

The size of the place is impressive: 60 50m posts, 65 25m, plus a finals range, skeet, trap and all, plus 80 air conditioned 10m post. The figures to stick egg boxes are staggering, imagine a proper job with something like Sonex.

Some executive jets use less padding and sonic suppressor systems. I imagine that something like that could be cheaper than any other solution.

Anybody knows somethig or someone that knows about the subject?

[Spencer]

We have a nice range in Rio, copy of Sidney's. As it happens, the copy was sloppy, and there is no acoustic treatment on the thing. When 8 shooters are in Rapid Fire conversation stops all over until the blast is over.

The size of the place is impressive: 60 50m posts, 65 25m, plus a finals range, skeet, trap and all, plus 80 air conditioned 10m post. The figures to stick egg boxes are staggering, imagine a proper job with something like Sonex.

Some executive jets use less padding and sonic suppressor systems. I imagine that something like that could be cheaper than any other solution.

Anybody knows somethig or someone that knows about the subject?

Do not have any mistaken idea that there was any consideration of 'acoustic treatment' at the Sydney range during the initial design:
- Sydney was a half-baked (i.e. sloppy) copy/modification of Barcelona. Barcelona has (had?) proper acoustic design between the 25M and 10M ranges: getting the single layer of glass wall at the back of the 10M range at Sydney was a drawn-out fight
- the number and size of the additional rooms within the Rio complex make a mockery of the non-target facilities at Sydney

[Hemmers]

I can't see that active noise control would be much cheaper than egg-boxes. It's just acquiring that many egg-boxes would be somewhat of a challenge! Have you considered just hanging sheets or curtains against the walls, which I assume are concrete?

Any loose material able to absorb air movements will help break up the noise and reduce echoes.

A prone-rifle range I've shot at has a wall between the firing point and the range proper (i.e. you shoot through windows). The barrier is a wood-frame with bubble-wrap stapled on, which absorbs sound from the range most effectively. Not appropriate on an ISSF range, but hanging bubble wrap against the walls in another option instead of sheets/curtains.

Also, they had carpet tiles all the way down the range, which absorbed noise which would otherwise have echoed off the concrete floor.

A possibility for indoor ranges and firing points.
OK, shooters will want to stand on concrete, not carpet, but everything behind the actual firing position could be carpeted.

Again, money, but even just carpeting some areas would make a difference. I don't know how easy it is to get offcuts on the cheap from carpet wholesalers in Rio. We had one in the UK for our clubroom. It was a hard-wearing carpet where they had laid down several thousand square feet for a convention centre or hotel, and for a nominal sum we managed to pilfer an offcut big enough to recarpet our clubroom. We ended up getting something like an 80% discount compared to if it had been delivered and fitted by the company as a normal order, because they would only have binned it otherwise. It would have been far too small for any of their other jobs.

I assume the other problem is not just the acoustic design of the range, but that you are shooting CF pistols, which are naturally much noisier than the .22s, and as you say, the .22s are an issue on rapid-fire courses.
In which case, could remedial action like I've suggested be applied to the areas used for CF and/or Rapid shooting, which would save money compared to doing the whole lot.

[jacques b gros]

In parts: you buy brand new egg boxes, in the color you choose, at the factory.

The size of the range is staggering: besides the number of shooting posts, the place has some 15m from floor to ceiling, making space for seats and some 5m more above the top seat tier.

Now, some 60m lenght times 10m ceiling width = 600 sq meters. Plus walls: 15m height times 10m lenght times 2 walls, more 300 sq meters, for a total of 900 sq meters for the 50m range only...

double that (adding the 25m range) and we're close to 2,000 sq m. Estimate a price for the insulating material in the US, double it (taxes) and add glue and labor.

Lotsa cash...

[RobStubbs]

<snip>

double that (adding the 25m range) and we're close to 2,000 sq m. Estimate a price for the insulating material in the US, double it (taxes) and add glue and labor.

Lotsa cash...

Then do as Hemmers suggested and add some cheap (old) sound proofing materials. Strips of old carpet, old blankets etc, anything to 'soften' the concrete walls. If you just do bits you can then see how good that is and avoid paying out a small fortune.

Unfortunately a big range is never going to be cheap to sound proof.

Rob.

[jacques b gros]

[/quoute] Then do as Hemmers suggested and add some cheap (old) sound proofing materials. Strips of old carpet, old blankets etc, anything to 'soften' the concrete walls. If you just do bits you can then see how good that is and avoid paying out a small fortune.

Unfortunately a big range is never going to be cheap to sound proof.

Rob.[/quote]

C'mon, Rob... the place is called Natl Sportive Shooting Center, can't dress it in rags...would be like using leftovers to upholster your Parliament seats: no two alike...

Cheers!

[RobStubbs]

C'mon, Rob... the place is called Natl Sportive Shooting Center, can't dress it in rags...would be like using leftovers to upholster your Parliament seats: no two alike...

Cheers!

Well perhaps if you'd stated that upfront, you might have got a more appropriate suggestion.

Do it properly then and spend a small fortune in doing so. If I were doing this I'd speak to a range design consultant and follow their suggestions, but that will also cost you. That said I would have implemented that at the design phase and got it fully configured in the first place - an add on to a finished design will always be the more expensive route.

[jacques b gros]

Rob,

The problem with the range is that it was built by the government for the Pan American games, and NO shooter had anything to say. It was delivered to the NGO some 20 days before the games...Budget for the games was less than 20% of actual cost. That is, cost was 4 times budget...

One example: the wiring of the targets was running just in front of the firing line, and EACH post had a metal cover on an access hole, where the wiring of that post's monitor spliced onto the cable. This was not level with the floor, and exactly where the front foot would be.

We had to move back the whole line some 40cm, so the targets also moved same distance. Consequence: targets came out from protection against rain and sun. Shadows were projected on them, so a translucent cover was provided.

Why it was done this way? If you get a leftist government, full of people trainned in Cuba, who has already nominated some 65,000 party people into key gov. positions, you can understand why corruption is rampant and a union chief, with no technical background, becomes president of a high tech company...

[Hemmers]

It is a problem if aesthetics count as well.

I don't know what's available in Brazil, but in the UK we have Primark and various factory outlets selling "seconds" (quality control rejects), and dirt cheap clothes and soft furnishings.

If you could obtain a truckload of new, but very cheap sheets at a discount price, then they could be hung tastefully as drapes against as many walls as possible (again, difficult if you have spectator stands, etc). Even just getting drapes against the back walls will acoustically soften the room a bit. You could also hang them below the ceiling if fire regulations allow.
They don't need to be particularly expensive or good quality ones as you're just going to be hanging them up and leaving them there. Any marks or faults (i.e. the reason theyre so cheap), can be hidden by ensuring they're at the back of the concertina when you hang them loosely.

It's the only way you're going to do it without spending big bucks on range design consultants and electronic noise abatement.

Also, although you don't want it permanently draped in rags, if offcuts and bits of old carpet could be found, it would be worth dragging them in for a bit when there are no big public events on, to assess the relative impacts of wall drapes/carpets/ceiling drapes before you acquire a solution that is aesthetically worthy of the venue.

[Tim Conrad]

Active noise suppression works well in headphones, with a limited "target" area, your ear. Over a large area, like a shooting range, not practical. Egg crate foam is about the only reasonable option.

During the actual shooting part of Rapid Fire, nothing works very well.

[jacques b gros]

Well, a talk with someone in the industry told me that active suppression is out, won't work.

So, back to the old stuff. Had the idea of hanging Styrofoam behind and above the shooter, another tier behind that to catch ground reflections on their way to the ceiling and glue panels to the walls. And work only in the 25m range, since this is where most of the noisy is.

Hope we have this at least partly solved before the 10th America´s Championship, to be held in Rio in the 2nd half of November...

[JamesH]

Can't you just hang curtains on the walls and at intervals across the range (ie parallel with the firing point - like baffles)?

[jacques b gros]

Can't you just hang curtains on the walls and at intervals across the range (ie parallel with the firing point - like baffles)?

That is the idea, but with styrofoam because it can be made in the color, is lighter to hang and easily replaced. And problably blown in the wind...

[Hemmers]

Another idea to throw in the ring.

A friend has just kitted out a "band room" in his house. It is lined with carpet underlay.

Looks quite smart if you can get it in a tasteful shade of grey or black. Sadly a common one seems to be a rather horrid green which you wouldn't want strung up in a National centre. It acoustically softens the wall in much the same way as eggboxes and may well be sourced cheaply as surplus/offcuts from carpet suppliers.

[Tim Conrad]

Most of the sound comes from the muzzle of the gun, with some from the ejection port. It is close to a 'point source'. You also get sound off the trap, less of an issue outdoors. If you only had to worry about the source, the gun itself, it wouldn't be that bad. But sound radiates in all directions, and most of what you hear is reflection. Off walls, tables, floors, almost any hard surface. Minimize the reflection and you minimize the noise. Carpet, particularly with a heavy foam back can work. Styrofoam is not as effective, too light weight. Need more density. Lots of folks sell sound absorbtion stuff for industrial applications. And charge a bunch for it. Carpet on the walls may be your best bet, particularly if it is not hard attached. Hang it or soft foam behind. Tables and floors are more of a problem as they will collect lead. Mostly primer compound. That was a real problem at USA Shooting, we were far over the limit for lead concentration. You may not have those rules yet, but sooner or later the bureaucrats will run out of things to regulate and come after you. For those surfaces, something you can clean. Soft and cleanable is probably expensive.

[jacques b gros]

This is the thing. Old pic, grass is greener now.

From the right, facing south (don't forget, other hemisphere):

Finals' range (installing electronic targets 2nd quarter 2010)
25m range, 50 posts
50m range, 60 posts
Skeet and others, 3 ranges

Facing north the 80 posts 10m Air range and offices.

Connecting both a 2 floors corridor, a "mere" 280m long (measured on Google). No wonder a RO is 3/4 dead after a 4 day match.

Notice that there is no heat outlet in the long ceiling, and the thing is horizontal. If the breeze takes a day off, the 10m range gets crowded.

the flat roofs add to the noise and traps heat. Someone forgot to check the weather...

[PL]

If the roof can take the extra weight, grow some native plants on it. Look up the term "Green roof". It will reduce the heat, at least. Might even reduce some noise because it will be thicker & more rigid. (just a guess) Most sound reduction, of course, needs to be inside.

[Hemmers]

A green roof would doubtless look nice and yes, probably absorb some heat, as well as insulating the roof in winter.
However, plants outside will do next to nothing for the noise inside, since the noise is being generated indoors, although they might reduce noise pollution in the surrounding environment, which is always a plus.

In summary as people have said, viable options run to:

- Carpet on the floor
- Carpet on the walls
- Drapes/curtains/sheets against the walls
- Drapes/curtains/sheets hung from the ceiling either in place of ceiling tiles or as baffles every few firing points.
- Carpet underlay against the walls
- Ceiling tiles (on ceiling or attached to walls)
- Egg boxes
- "Eggbox carton" foam as found in rifle cases, etc.