Does anyone here have any experience with improving acoustics in large room?

Here is my problem; I am trying to improve absolutely horrible acoustics in a building that has a quonset (arch) type of steel roof set on 12 foot high concrete block walls. At one end is a small stage, but the other three walls are relatively plain except for a couple of doors and support columns. The floor is about 75' X 85'. Nothing to restrict bouncing sound.

One of the problems is that this is a multiple use building. On Sunday's it is used as a church, but during the week it is also used as a sports area, so ***** get bounced off the walls by boisterous kids.

Have been reading on the internet about how to improve acoustics in this style of building, but everything I have read does not seem to take into account the inadvertent damage that playing kids can do. Also, finances are very limited, so need to find a way to do this cheaply. At the same time, want whatever we do to be aesthetically pleasing. So how do we get the best bang for thin bucks?

 

It's always fun to try to get enough volume in a room with the acoustics of a coffee can. That' one of the main challenges to a Baptist sound man.

1. Fill it up with people. That always improves the acoustics.
2. Anything soft hanging on the walls, cloth art work, gym mats, egg crate foam, etc.

You can compensate somewhat, usually enough, by mic placement. I find that a body pack with the ear mounted mic placed within 1 inch of the user's mouth and with the appropriate protective cap (countryman e6 mic on a shure body pack) give enough clean input that the reflected sound isn't a big factor. This stuff ain't cheap, but it's pretty high quality and pretty rugged.

On set mics, such as a podium mic. Use a highly directional mic, and then compensate with a 15 channel or more equalizer. Set up the equalizer by putting white noise on the speakers, and adjust the equalizer examining the mic pre-amp output with a spectrum analyzer. You want it as flat as possible. You'll find the equalizer is pretty jagged when it gets set up, as you've tuned out the feedback resonance points, and filled in the flat spots. That tuning is messed up when the mic gets moved, so break any fingers that get too close to it.

With hand held mics, put a wind screen on them and teach the users to leave teeth marks on the wind screens. I've found that it's easier to teach the kids how to use a mic than the old folks that seem to be afraid of it. I explain to them that if they get the noise into the mic, I can always throw the excess away. If they don't get enough noise into the mic, I can't do anything with it.

Also, if your mics are worth anything, break any fingers that tap the mics to test them. You test a mic by saying words into it.

Another point is that the worse the acoustics, the more important monitors are for musicians. They need fairly clean feedback so they can blend. Monitors are placed in the null area of the mics, so they can be plainly heard by the singers without causing feed back.

If the budget can stand it, it really helps to use a dsp (Digital Sound Processor) like and Ashly Protea 24.24 . If you use multiple output channels and speakers along the walls, or even along the ceiling, then set the sound to delay to each speaker what the delay would be for sound traveling through the air (the calibration is in feet, put the slide rule away) then the sound to the hearers feels like it's coming from the front, but a large part of it is coming from the auxiliary speakers. Done right it sounds good from anywhere in the auditorium.

hope it helps
john the baptist sound man.

 

John the Baptist, thanks.

It's not just the sound system that is a problem. The main problem is without any sound system. Any sports in there creates horrible noises. Even without extraneous noises, I can't understand what someone is saying to me if they are about 30 or more feet away. That is due to the vicious echoes. Have been thinking about what to do with hanging stuff. Can obtain new egg cartons cheaply and glue them all over the place, roof included and paint them. That does not look very good, but should work. Need something better and stronger for the lower walls where kids and ***** bump into them. Don't have time for weekly repairs.

BTW, do you eat locusts too?

 

DUH - - - you don't. ................Delicious

John gave you some great ideas, but they cost money and mostly about the sound system. Both your front and back wall are probably flat. Many will work on the back wall but not the stage. In your set up, you will get a lot of bounce from all the walls, but you are limited to what you can do on the side flat surfaced due to sport activities. You can work on the end walls. You probably to not want to spend a lot of money, so think about breaking up flat surfaces. Make large eggs crate style cavities up a little higher on the walls out of wood. Cover them with sound absorbing materials as well as the flat wall surface and here I don't know what you would have available. Be creative. Sometimes they will make these as say 6'x6' or so boxes about 8 - 12' deep with divisions in them about every 2'. They will make these and then mount them on the wall so they look attractive every 4' or so apart. You need to think about this on both ends. This is a rather inexpensive start on sound deadening. I have seen thick drapes hanging from the ceilings across the arch in quonset style buildings down as far as practical following the arc about 4' long and every 8 - 10' or so. Your flat hard side walls create a problem - - not much you can do with them due to usage.

Good luck.
Bob

 

a coffee can is an excellent description.
Do the kids utilize the entire height of the quonset for their sports? If not, hanging heavy curtains with 8ft between each row of them will reduce echo.

Is there anywhere where you can do carpet runners? You could even run carpet on the arch if it looks good.

Deadening the ends works too.

As for the concrete...we hung gym mats all along the cement walls of a place nearby. The gym mats were the old style mats from a salvage place. It worked ok...not perfect but it helped as long as the arch of the ceiling had the curtains. The padded walls, LOL worked well for the kids as well...especially the big kids like myself. Could slam into a wall and carry on laughing.

 

They used a rubberized paint in our hangar that made a huge difference on noise. The construction is similar, block walls. The paint is tough and stands up to abuse well. Might be something to look into.

 

See now, all along I thought the rubberized paint on the walls of the hangers was to minimize your injuries when you were having a tantrum and throwing yourself off the hangar walls....

 

This is a great start to the derailment of the topic.

Padded rooms are great. I just don't like the jackets with really long sleeves that come with the room.

 

Back to topic. Any shape or material that absorbs sound (foam) or deflects it in a wide variety of directions (egg crate) is going to help.

An outfit I worked with making the plastic for fishing baits also makes a vinyl sound deadening product. I think it's main ingredient is dirt. (clay)

It's Loes Enterprises in St. Paul, MN. Small outfit, but very into solving problems with vinyl.

 

And still on topic...
A company right here in my home town manufactures a product called brown bread for sound deadening...comes in rolls not loaves.

 

In my long ago life, I worked with antenna design in an anechoic chamber. It was carbon coated high density foam. Looked like lots of teepees glued everywhere. It almost completely knocked the sound down to nothing. If you were facing away from your coworker, you couldn't hear each other. I was told at the time that the shape of the cones was the key. It would be lots of work to mount it on your arch, but maybe this idea would help.

 

Thanks everybody for all the advice so far. Never expected such a response. Y'all are great.
Will now take your collective wisdom, do some head scratching and see what we can do.
Thanks again.

 

Stan - - just noticed a mistake on my post and it would not let me EDIT it up there. So, here is the change in bold - - 8 - 12 inches deep, not feet. DUH - - sorry about that. Incidentally, I have seen this crate setup on end walls of many churches.
Bob

 

I stopped doing the self abuse thing when I ,,,,,,,, wait this is not sounding right, is it.
I don't have tantrums, I have retaliations. It's the people that make me I bounce off the walls.

 

one more thought. from the cheapo, post-apopalictic tin foil hat folks....

unsold remnants of carpet squares (or cut to four foot by four foot) applied to the walls about every six-eight feet, and four feet up from ground. some ceiling areas are suspended by cable in the top center of the remnant, so the supported panels can freely rotate. a mic test would tell what height is maximum benefit.

bosnians said it works very well. wish I could help ya.....