BISERICA SPERANTA ACOUSTIC Assistance

[cmchamp]

I think were the room a restoration of a historical cathedral or other large liturgical space where every minute detail of the rooms response was necessary for the acoustical analysis, the minute differences between a balloon pop, yachting canon and dodecahedron array are minimal.
Yes, from experience, it is difficult to get consistent output levels from balloons, that's why it has been recommended to me to utilize a minimum of 8 balloons in those tests. Yachting canons for large spaces, I can understand because of their regularity in load, however, way overkill in small room acoustics and they can possibly cause damage to both the room and the measurement microphones. I've done some reading on the dodecahedron testing, but so far, the testing I've done in the past number of years necessitates only the balloons.
C.

[Brad Weber]

Cory, I was not recommending using a yachting cannon for this application or suggesting that a balloon pop was not still commonly used, just pointing out that there are various approaches used. I attended a presentation by Peter Mapp that included, in typical Peter fashion, a very humorous presentation of research he did into the details of balloon pops as an impulse source, next time I see Peter I'll have to ask if he can post some of that on his web site.

Along with averaging out any inconsistencies in the source, you typically want to make measurements in multiple locations in the room as, which Cory often very correctly points out, most rooms are not a truly reverberant environment and conditions can vary, including sort of 'micro-environments' in and under balconies, on the stage, etc.

What really worries me more is that some of the tools that can present reverberation time values are not real clear on how they derive the values. Measuring reverberation time is in effect a curve fitting and how you perform that aspect can have a significant effect on the results. Not all instruments that offer reverberation time measurements do so based on accepted standards or present sufficient information to verify the validity of the measurements and results. I've seen people claim very questionable, and in some cases rather outrageous, results for spaces using some of the less expensive devices that simply present a numerical result for RT60. I have to believe that those results are likely be a result of the process used to determine the numbers and the absence of verifying the validity of the measurement.

[cmchamp]

I was just conversing apparently too late at night. Maybe not late chronologically, but mentally.
Just trying not only to continually learn, but, sometimes through my own understanding, allow others to clarify the aspects of this truly difficult subject.
More later, I've got to get guitar tracks to "You are my sunshine" recorded in 7 minutes.

[cmchamp]

I was perusing through some old email, not really sure what I was looking for, but ran across this from 3 years ago.

Here's my initial reaction to an "acoustic" report possibly a member of this community forwarded me. Names of the "consultant" have been removed.

_____
I received a copy of a rather shotty report by him with absolutely no documentation presented for tested (real) RT60 values or calculated (estimated) end results other than stating that the end RT60 would be 2.6 seconds.
Mr. XXXX also claims that "very little could be done to reduce the low-end noise that is extremely loud at 31.5 to 63 Hz" due to the air handlers as well as instrument noise from the PA system.
No documentation on NC values, noise floor, RT60 times, target SPL for the sound system, etc. (Mind you he wasn't there for the sound system, but it's all related.)
Anyway, I'm gonna tell the contact person in Lake Forest, IL. to hold on to any money they have for this project because I don't believe throwing 112 2-1/8 and 1 1/2" Respond fiberglass panels on the walls will do the job properly.
What say you? No, I do not have dimensions or anything else to base my judgement on but intuition.
Flags - in my opinion are:
1: No credible documentation - no starting point figures - no estimated ending figures other than an end RT60 target of between 2.6 and 2.8 seconds.
2: No diffusion introduced into the room - all absorbers recommended
3: No LF absorption to control the LF RT60 time, standing waves, etc. (note mechanical room is under the sanctuary and causes a wall to vibrate)
4: No documentation.
Food for thought.

____

After follow up info from the client. . .
____
Well, come to find out Mr. XXXX didn't use anything other than linear measurements to make his report. Had a dB meter, but didn't use any sound sources at all to find the RT60 time of the room. The contact is working on getting permission to get me down there to actually test the room and make a more comprehensive report, more aesthetic and cost effective recommendations and get my opinion on the HVAC noise.
It's my understanding that the mechanical room may be directly under the platform, so adding structural mass and/or isolation suspensions for the HVAC runs may be the best option.
____

Note, nothing ever happened of this, I never went to Lake Forest IL.
This is an example of Chad's concerns regarding ill equipped "consultants."

Now, I'll admit, when it comes to mechanical isolation, I know the fundamentals, and know enough to know I know enough to recommend someone else for the job.
Room acoustics, especially small room (and we're not talking home studios or studio spaces either, those are another nightmare) acoustics I have a pretty good grasp of.

Words of caution for the soft stuff believers. Even when a dry room is requested, I believe it is best to keep some diffusion in the room for the following non-inclusive reasons (remembering also I'm a classically trained musician, music teacher and southern gospel tenor)
1: spacial feedback for the musicians that aren't on in ear monitors. I teach my students, both vocal and instrumental, the farthest person who needs to hear you is you. Even in the midst of a band, one should still be able to hear themselves through it all from the house sound system. Difficult to do if there are no reflections heading back to the stage. I find an extremely dry room more difficult to sing in than a highly reverberant gymnatoria.
2: excessively dry rooms are uncomfortable and not intimate
3: excessively dry rooms with an abundance of soft stuff tend to have over-exaggerated LF standing waves. Not because the "soft stuff" changes the LF frequencies, but because there are no MF and HF frequencies masking them.

[mifantrax]

Regarding the speakers suggested, what would be a good amplifier to team up with the evi's ?

[Brad Weber]

Originally Posted by cmchamp

3: excessively dry rooms with an abundance of soft stuff tend to have over-exaggerated LF standing waves. Not because the "soft stuff" changes the LF frequencies, but because there are no MF and HF frequencies masking them.

The old "peeling an onion" analogy that I have to use quite often with architectural acoustics, once you deal with the most obvious problems you may find other issues that then become more apparent.

[mifantrax]

Hello dear Churchmedia, I had a really tough period due to christmas activities, final exams, i would like to aproach again our church acoustics problem.
If you have any other ideas please tell us.
On our website are videos recoded with a camera and mic that may help you some to get an opinion on what our problems are untill i will post the baloons test.
thank you

[mifantrax]

I found a few papers on acoustics also a few books that i am reading hoever this article killed me.

http://www.prosoundweb.com/article/p..._quality_sound