Ideal acoustic space

[buggyboy]

So,

if you were to start from scratch, no budget concerns, no preexisting walls, nothing but a blank slate.

What would you do to get as close as possible to "the ideal acoustic environment".

goals:
-this will be a sanctuary.
-it will hold, oh, 300 people (or use the number you like).
-it will be excellent for amplified speech, capable of very loud levels without feedback.
-it will be very good for amplified traditional music (vocals,pianos, organ, acoustic guitar, etc)
-it will be tollerably good for modern music (drums, electric guitar, etc)



given those goals:
-what shape of room? (rectangle? diamond? fan shape?)
-what dimensions? what are the important relationships between the proportions?
-what angles (right angle wall junctions?, vertical walls or off vertical, etc)
-what materials used?
-what design of pa system (line array, center cluster, etc)
-where are speakers located?
-what height of stage?
-what floor covering
-what seating
-what location of sound booth


the point here is that most churches build the building, then fix the acoustics...but what would the starting point look like if they started form an ideal acoustic space, then made the other issues bow to that.

[petereit]

I'd have Lonnie Theer design the sanctuary and have him work with my architect to fill out the rest of the building.

[cmchamp]

Buggy
I believe part of the reason churches wind up going backward is they can't foresee the expense of correcting a poor room when weighed against or compared against the cost of pre-planning and proper design with a team of qualified consultants, especially for the scope of a 300 seat room.
There are "golden ratios" for rooms to properly distribute the mode/node of LF energy specifically for "studios" as specified in F. Alton Everest's books and others. I don't have that information on hand to share.
There is much more that goes into acoustical design of a building besides just it's shape, substrate, building materials and finish materials. STC values between rooms (sound isolation), HVAC noise floor, noise floor of architectural lighting and controls, absorption of seating, % occupancy, etc.
More later - gotta go record my lessons for tomorrow. (public school music teacher)

[buggyboy]

To clarify, this is once again an education question for me. No projects in the making.

No one ever has to sell me on the idea of bringing an acoustician at the design stage. In fact, I would find it altogether pleasant if the main posters on this board would stop bringing that up. (I love ya'll to death and this board, but after awhile it sounds like "eat your peas, son")

If I ever have ANY voice in ANY building or design process, rest assured I will speak loud and long requesting an acoustical designer be hired. The flip side of that coin is, if I don't have the power to bring in a design consultant, I don't have the power. If I'm posting a question in an online forum, it means I have no other choices. I'm sure that for most people posting, services WILL be held, come high water, bad acoustics, or power failures.

In the same vein, anyone techy enough to post in online forums should know that the advice given is not a substitute for legal, medical, or acoustic consultation with registered, certified, professionals. So the objective for 95% of posters is to get the opinion of someone who knows more than themselves, then try something cheap.

Just trying to say that the most common responses of "you should hire a designer" and "there are thousands of variables, your idea may not work" are not helpful to the vast majority of posters who have no money, no power, and just want to try something to make the sound better.

alright, end rant.

as to the ideal room. Granted there are about 14 million details to consider. The heart of the question is, "what major elements contribute most to a good acoustic space?"

I just read some excellent articles by Arthur Noxon here http://www.church-acoustics.com/aa101.htm

Who at very least does a great job of explaining that you want different "zones" for different purposes.

for example, for sounds originating from the congregation area you want a "live" space with plenty of hard surfaces (not all hard of course) so that the people can hear themselves sing, encouraging better singing (the flip side is that you still need some control for sounds like scuffling feet etc). same for any choir loft.

while for sounds originating from the speaker you want good direct sound, good early reflections, few or no late reflections and a reasonably low reverberant field.

He talks about padding the stage side of beams while leaving the seating side bare to present different characteristics to the sounds coming from different sources.



So, given all the complexity, What are the biggest factors?

Given my reading, I'd tend to suspect a traditional rectangle with the stage on a small end, with a somewhat vaulted ceiling going from about 15 feet near the stage to maybe 20 -23 feet in the center then declining again to 15 feet near the back. (the sound should hit the rise and project some early reflections out and down, the back decline should add some good reflections in the rear seating, the non-parallel between ceiling and floor should cut down that mode and reduce flutter echo.)

The side walls should probably angle around 10 - 20 degrees. Getting wider moving away from the stage. That should again help with modes and flutter echo.

The back wall might be angled slightly so that the top is nearer the stage than the foot. Directing sound down onto the seating area.

center hung speaker (cluster if needed for coverage) for voice reinforcement (pastor, soloist, music leader) adds to localization.

Music speakers on each side, in the air at least 2/3 of wall height.

carpet on walkways, aisles, etc. no carpet under pews.

Presumably, one would ideally completely soundproof the entire envelope of the sanctuary so that no outdoor sound could intrude (practicality likely prohibits this in most situations.)

those are some guesses anyway. Like I said, it's a academic mental exercise for me. my initial feelings may be hogwash, but it's something to get the ball rolling.

anyone ever done a circular room?

thanks

[petereit]

OK, if you had STARTED with "this is an education question for me. No projects in the making", you'd have saved yourself all the "eat your peas" comments.

[Brad Weber]

I realize the point is educational but a reality check is that there are numerous other factors to consider and you can't approach the acoustical aspects in a vacuum. Sightlines, worship style, budget, aesthetic preferences, etc. all factor into aspects such as the room dimensions and layout. A church that wants a traditional look may require a different approach to room acoustics and audio than a church looking for a contemporary or industrial look even of the acoustical goals are the same. Many of the same basic concepts may apply but the materials used and how they are implemented may differ significantly.

A simple example of all this would be one I have actually encountered. Three similar spaces in terms of capacity, worship style, goals and so on. The first space was one where probably the primary goal was being a very traditional appearing space and the building is a standalone structure with minimal ancillary or support space as it is connected to an existing building that had a larger auditorium style worship space. The second project was a contemporary worship and event space that was part of a larger building construction where the worship space is pretty much surrounded by other spaces and supplementing an existing traditional worship space. The third project was one of these, http://products.sprung.com/productList/1037527/1000816. All three required very different approaches to acoustics and audio despite having similar goals.

A clear example of how those differed is mechanical noise. For the larger project we could locate the mechanical equipment in less acoustically critical areas of the building and have long, straight duct runs to help reduce noise levels in the worship space. In the traditional space there was no space to go out, so we had to go down and the mechanical systems are located below the worship space, which allowed longer duct runs, etc. but created a major sound isolation issue to address. In the sprung structure any mechanical equipment space had to literally be carved out of the worship space and there was little to do in terms of isolating the building from exterior mechanical equipment or other noise sources, requiring relying much more on quieter equipment to start with.

There were many other differences including the finish materials used and how they were applied. There are some who do try to distill all of this down to a checklist approach but I think the above example shows the fallacy in that.

[buggyboy]

Thanks for chiming in Brad.

I'm really at a loss of how to communicate what I'm trying to do.

Ignore the sight lines, budget, aesthetics, etc. They are a compromise for later in the design process.

I detailed the programming the room will see, in order of concern.

At some level acoustics is math. Starting with sound propagation from a point source.

add in the effects of walls (cube, rectangle, triangle, sphere, etc)
add in atmospheric effects
add in absorption by people and furnishings.
add in speaker directive.
add in open mics
add in etc etc etc

all these addons are additional functions that modify the original equation.

Now, i hate math, but turning the math into English should give us some decisions like a perfect cube being a terrible shape for a sanctuary as all the modes are the same, etc etc etc.

I hope this is making sense...i just can't get the words out today.

[audiomatic]

There's a lot to consider in this thread, but I'll have to read through it again when I have more time and when I'm not so tired. But I do have 2 cents about the ideal space for a sanctuary or worship center:

1 cent: People seem to sing out more enthusiastically when they can hear themselves as a group and hear a little reverb in their voices.

2 cent: People zone out when speech intelligibility is poor during the message. The first recorded instance of someone falling asleep in church was when Paul was preaching in the upper room and there was so much reverb Eutychus was having trouble understanding what was being said (Acts 20:9).

Some compromise between a reflective ceiling over the congregation and focusing the sound energy of the message where it needs to be would approach the ideal worship space.

[buggyboy]

thanks audiomatic, that's closer to what i'm talking about.

let's imagine a source of directed sound (standard speakers) hanging in space above and in front of a plane of seated people. No walls, no floor, etc. All sound would be direct sound. gain before feedback would be huge so long as the mics were kept behind the speakers.

if the seating area were very long we would be forced to either move the speakers very high (to get the same distance from speaker to front row as speaker to back row) or set up delay speakers midway back.

if the area were very wide we would need to hang speakers for each section since the first set would cover the rest.

in any of these cases there would be no echos or reverb.

it is in adding the walls our first obstacle appears. because any wall might give us good reflections, bad reflections, or just serve to hold acoustic energy as reverb.

so, what walls will help us?

sound taking one bounce off the back wall should be a good (early) reflection if the time taken from speaker to wall to audience is less than 60ms. (I'm to lazy to do the math now, that's like what, up to 100 feet from speaker to wall?) if the space was longer than this that back wall would be a source of bad reflections for the front pews. if the back wall was angles to direct sound down into the seating, it would still be a source of good reflections for the back rows while the front rows would be spared the bad reflections.

((is any of this making any sense? am I off my rocker? ))

more later...
Thanks

[cmchamp]

I had worked on your comments regarding your speaker placement for the orientation, but lost it. Maybe later.

Regarding "early reflections" in design, it is my understanding from reading that early reflections source should come from side walls and clouds above the stage, not from behind, as reflections from behind cause disorientation and fatigue. Additionally, early reflections should range between 20ms and 40ms. 60ms would be a difference of about 67.5' between the loudspeaker => listener and the loudspeaker=>reflection=>listener.

In all the years I've been working with sound systems, room acoustics, etc. reflections off the back wall (flutter echo or slap-back) are supposed to be reduced.

Additionally, any RT60 calculation is only a true "reverb decay -60dB" measurement IF the room in question is diffuse. A diffuse surface will sound waves in a scattered pattern, rather than the angle of incidence is the angle of reflection scenario as off of hard flat surfaces.

I'll address wall surfaces as to what will "help" after a meeting this morning.

[Brad Weber]

I understand what you are trying to do but the challenge is that "worship" encompasses such a wide range of situations and goals. It's much easier to address general acoustics issues for a particular situation but much more difficult to address that for 'worship spaces' in general. This is an important part of what Doug Jones' new book "Sound of Worship" addresses. Just look at some of the more recent trends in the approach to worship and the associated spaces and one common one is a a move away from large speaker-to-audience oriented spaces and toward smaller and more interactive or collaborative oriented spaces. These also associate with two potentially very different sets of acoustical and audio goals. Perhaps a good example of this is Audiomatic's comment about congregational singing. His point is very valid, however nothing was mentioned that actually indicated that congregational singing was involved and support of congregational singing is not necessarily a factor, or even desired, in all worship spaces.

I also understand the desire to want to disassociate the other elements of the facility design but that is simply not a practical approach. At least in my experience, for the vast majority of churches, including some that initially indicate otherwise, the issue is not what would be ideal acoustics but rather what are the best acoustics possible within the limitations imposed by numerous other factors. For example, a worship space's basic construction can very well affect acoustics and the resulting approaches and treatments, however it is quite rare that acoustics alone will dictate whether masonry, steel structure with infill, wood or metal framed, timber framed, etc. is used. Seating is another good example, if a goal for a worship space includes intimacy then that likely affects both seating and acoustics and in ways that may conflict (e.g. fan shaped rooms and rooms oriented on a bias). There's also related issues such as avoiding a disconnect between the visual and aural experiences, people trying to reconcile a space where the look and sound don't correlate can be distracting. As a result, I find that it is understanding the implications of the deviations from the ideal involved and how to minimize the impact of those deviations that is usually more important than knowing what would be ideal.

But to perhaps get to the real point, quite bluntly what happens with most "what should a church do" questions is that it is really someone asking "what should my church do". There is nothing wrong with that, it just has to be made clear and any responses taken in the context or being predicated upon that particular situation.

[buggyboy]

Let me say this again, even thought I can't believe I've had to say this, what, 4 times already?

this. is. academic.
Any resemblance to persons living or dead, places, location, etc,etc,etc is accidental.
this. is. not. a. practical. design. class.
the designs we discus here will never be used because, as you say, it isn't practical to build a church for ideal acoustics.
practical churches must deal with sight lines, seating, hvac, etc,etc,etc.


However, our imaginary church is always 72 degrees and fluffy clouds. our imaginary building committee will use whatever building materials the acoustic consultants asks for. they'll thrown out their notions of aesthetics and allow the acoustics to override all other concerns.


construction could be concrete, steel, timber, you name it...the imaginary building committee is totally on board.

as for shape...as far as the committee cares the people could sit on bean bag chairs.

if lights cause acoustics to suffer, the people can sit in the dark.

All other considerations will bow to acoustics in this imaginary church.