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Posts Tagged ‘drywall’

Dead Spots – Sound System or Acoustics?

Posted by jdbsound on April 9, 2018

An unwelcomed guest in any church is Mr. Deadspots. Unfortunately, deadspots in churches are more common than you think. There are two main types of deadspots. Some are frequency related/comb filtering interference and others are dips in sound levels greater that 6dB created by the room.

It is common to see frequency related deadspots in Left/Right sound system regardless if they are Line Arrays or point and shoot speakers. These deadspots are created by interference patterns in a mono speech system as a persons voice is always mono.  These deadspots are where you shift from one foot to another and notice a sound change. In these cases it becomes a problem when on one foot you hear the highs but not the lows. When you shift your position onto the other foot, you hear the lows and the highs disappear. People with hearing aids or early stages of hearing lose notice this the most. People with good hearing notice the change too but learn quickly to put up with it. Some young people think of it as a passive noise filter. If the music is too bright, stand to one side of your seating position. If the music is too boomy, shift to the other side of your seating position. Really! Isn’t that like buying a headset and controlling the sound changes with what angle you tilt your head. It might sound like a great idea until you find yourself with a lot of neck pain. No thank you.

Sound level dips are usually acoustically related. These are created with standing waves, bass building up, hollow walls, room corners, and parallel surfaces that include walls, ceilings and floors and concaved surfaces. In all of these cases, often mid and bass energy build up and the highs are absorbed with carpets, padded pews and people. By the nature of churches and how they are used, carpeted floors and padded seating often represents how the church sounds when it is 50% full. That means that if your attendance is often over 50%, the effects of padded seating and carpeted floors has little to no impact. If church attendance is often over 70% a carpeted floor makes the room more intimate during times of prayer and solemn reverence. In the end, carpets and padded seating is a good thing.

However, because of people in the room, once that room attendance is above 50% the people absorb enough highs that extra mids and bass energy is left behind as is being amplified between parallel surfaces. This excess energy automatically masks the highs. When the highs are masked, speech and music intelligibility drops. The kicker is, if you go around the room with a sound level meter, often the sound levels don’t drop much, even when you stand in a spot where the highs (when you measure just the highs) drop off over 6dB. That is because the excess bass energy is so strong that it fools the sound meter as the meter is reading an average sound level. When you take sound level readings by frequency, then you notice the high number of deadspots in the room. Get a tone generator in a cell phone or computer app and play a constant tone at 55dB at 500 Hertz, 1000 Hertz and 3000 Hertz and then start walking around. At 500 Hertz you shouldn’t notice much of change until you get close to walls. At 1000 Hertz you will notice more changes. At 3000 Hertz, if you are hearing a lot of changes, imagine what 25% of your church audience is experiencing.

Here is a church that had both acoustical and sound system created deadspots, with a central cluster. By nature of a central cluster, in a good room, it gives the best coverage and performance for speech. There is no better way to design a church sound system unless your ceiling is less than 14 ft. high. Choice of speakers, coverage patterns and speaker placement impacts sound too but these are mainly tone qualities and gain before feedback related. It may have up to a 2 or 3% impact on overall intelligibility as well.

corner view pano Ebeneezer Church_s

In this church example, it already has a fairly good quality speaker system in the ideal location for the room. It is designed as a central cluster and by nature, in this setup, it should perform well. However, it didn’t matter if you used the main speaker system or used portable speakers on stands, with any sound amplified you could find deadspots all over the room. On top of that, if you raised your voice in the room, once you were more than 18 feet from someone, understand what was being said was difficult to impossible depending on dictions of the person talking and how good is one’s hearing. When the proper acoustical fix was applied, all of those problems went away and the church didn’t need to upgrade the speaker system.

The church decided to leave the sound system alone as the gain before feedback improved and all of the deadspots disappeared. Since this is a traditional church that has no intentions to do anything contemporary, the acoustical fix was designed to not change the overall reverb time. Before and after reverb time remained about the same. 1.7 seconds.  It was the frequency response of the room that saw a major change. As the graphs shows below, where the mixer for the worship space was located, it was also one of many spots where weird measurements were recorded before. We found dozens of spots where the room measurements went squirrely. This is typical of the results of measuring a Left/Right speaker system, not a cluster system. These weird results were a result of room acoustics and not the sound system.  We used our own test speaker for all room testing.

Sound Booth Before and After

After checking our test equipment for errors, it was then realized that by just moving the mic over a few inches, you would get a very different result. In some places, the sound was perfectly fine but move over a few inches and it was not. Our ears are about 8 inches apart. In one row of seating, the largest distance we could move the test mic between a good spot and bad spot was 14 inches. Pew seating is 18 inches.  Every seating position had both good and bad sound. What we were measuring was sound masking in the mids and lows.  The energy was so strong that it masked the highs.  Not only that but the highs were most likely also being canceled from nearby wall reflection between 1800 to 5000 Hertz.  It gave the impression that there was something wrong with the sound system.

In this church, people marked their seating positions by placing personal pillows in spots where the sound was better. Sure enough, testing these spots showed better sound before the acoustical treatment was applied. After the acoustical system was installed, the sound was the same no matter where you sat including the sound booth.

Deadspots in churches are more often a result of worship space design and not a result of sound system design (unless you have the wrong speaker system design for your room). When a church replaces a well-designed sound within 10 years, and have little to no overall improvement after an upgrade, that should be a BIG RED FLAG that you most likely have a serious acoustical problem and no amount of money spent on the sound system can make those problems go away. Besides, these days, acoustical fixes cost less than sound system fixes. As a caveat, our experience has been this. Churches that have fixed their acoustics and then wanted on to expand their music programs, they were able to upscale their sound system with a much higher budget as they upgraded, it actually lead to better performance rather than an exchange of one set of problems for another.

Bottom line is, get your church properly tested. Have someone who knows how to properly diagnose the data, and then design your church a proper acoustical management system. Install the acoustical system and watch the congregation respond and grow. Don’t be surprised if other churches want to use your church for musical and recording events. Your property value may go up too.

Note – The acoustical system is made up of 8 and 12 inch half round plaster covered foam diffusers on 3 walls.  The side walls use a gradient pattern to maximize room performance. On the back wall there are 24 units of 7 ft. x 2 ft. x 18 inch plaster covered foam diffusers that are hollow which allows for additional passive room equalizing in the near future. Project completed by church members.

By Joseph De Buglio
JdB Sound Acoustics

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New Church Sound System Equalization Schedule

Posted by jdbsound on February 17, 2016

Notice to all Clients of JdB Sound Acoustics.

If you are in a new church building or you have done major renovations in your church, you will have to re-equalize the sound system many times in the first few years.  Here is the Schedule you should follow.

  1. First year – After the 1st month, 3rd month, 6th month, 9th month and 12th month
  2. Second year – After the 4th month, 8th month and 12th month.
  3. Third year – same as year 2
  4. Fourth year – after the 6th and 12 month.
  5. Fifth year – same as year 4
  6. Sixth to tenth year, every 8 month.
  7. After that, once a year.

It take up to ten years for most building to fully cure or longer depending on how much concrete and wood is used.  For that reason, the humidity of the church becomes lower and lower as the church ages which also changes the sound of the worship space.

Also, depending on the climate area you are in, you should be re-equalizing your church sound system for each season.  more so the further you are from the equator.  If you have a digital processor or mixer, you can have presets for the room changes.

Joseph De Buglio

 

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What is the difference between scattering sound and diffusion of sound? Are Diffusers Programmable?

Posted by jdbsound on April 26, 2015

The simple answer is as follows.  Half, quart or third round devices or objects individually just scatter sound.  A single barrel diffuser or tube radiator as I often call them just create a very uneven distribution of sound.  As single units, it gives about the same amount of performance as placing a flat object of the same size and placing at a 15 to 35 degree angle on a wall.

When using barrel diffusers in various sizes and/or in spacing varying from 0 to 30 inches and apply them to all of the walls in a confined space, you are creating a diffusive field.  You’re turning the church walls into a phase coherent sound field – like churches of yester year built between the 1400’s to 1700’s.  When barrel tubes are used as a system you can program them to only manage the acoustical problems you want to get rid of and at the same time create a more desirable sound field like real reverberation that is musical and supportive to congregational singing.

Barrel tubes spaced too far apart just scatter the sound and reduces some bass but does nothing much else.  Instead, you can program the diffusers to manage standing waves, bass buildup, notch a frequency or two and equalize a room.  You can also program them to lower stage noise, manage monitor spill into the audience and improve congregational singing.  They can also be programs to make the sound system perform better.

The software to program barrel diffusers is still in development.  In the meantime, a test room, and a data base of real world testing is the best way to predict the final outcomes.  Try and program a digital EQ to cut 350 hertz 40dB.  It can be done but it sounds awful.  When you program tube radiators to cut 40dB, it sounds sweet.

Joseph De Buglio

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Question! What would you do to fix the Acoustics of this Church?

Posted by jdbsound on April 1, 2015

You have a church that seats 750 people.  It is a simple rectangle room with 30 ft walls, 40 ft to the peak, 80 ft wide and 140 ft long.  The reverb is 2.2 seconds at 300 hertz and 1.3 seconds at 2000 hertz.  An Energy Time Curve test show reflections over 30dB at one second on the ETC in the 300 hertz range.  The floors are carpeted and the pews are padded seats and backs.  All of the walls and ceiling are insulated drywall on 12 inch centers.  Basically there is about 30dB of excess energy at 300 hertz.  300 Hertz has a wave length of 3.75 ft. The church has already tried 4 different sound systems over 10 years and all of them were designed and installed by companies that are supposed to be the best in the business and they all started off saying that the room needs to be fixed – but church board members vetoed anything that would change the aesthetics of the room – but it was OK to hang 2 ugly line arrays which lasted only 6 months.

The church is now asking for another sound system but this time all of the professional audio companies turned down the project and said to the church don’t call us back until you fix the room.  Now the church board has relented and they are allowing acoustical panels to be mounted on the walls. What acoustical method or system would you use to fix the problem?  What will reduce energy 30dB in this space?

For all the walls in the church, between windows, doors and bulkheads, there is only 35% of the total wall space available to mount acoustical panels on. Major issues are – Stage noise, floor monitors as loud as main speaker system in the first 10 rows.  Only 20% of the congregation is ever singing. Speech intelligibility is below 85% in full range – if you roll off the sound system at 200 hertz speech intelligibility improves to 88%.  Gain before feedback is very poor after 3 or more microphones are turned on at the same time. Subs never really sound right.  Pastor hears echoes all the time off the side walls when preaching. Drummer can never hear himself or the other worship team members – even with the headset monitors. The are currently using electronic drums but they have tried drum shields and booths without much satisfaction.

The church used to have a 40 voice choir but they never sounded very good and now with over $150,000 invested in a praise and worship team with all the latest state of the art technology and higher trained sound engineers, they sound no better than what the choir did years ago – but they are better at entertaining people!

(note: this is a fictional church but this is based on actual events that have happened recently in three southern Ontario Churches.)

Joseph De Buglio

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Church Acoustics Advertising :-)

Posted by jdbsound on March 19, 2015

Do you have an echo problem?  We have a fix for that!

Do you have a reverberation problem?  We have a fix for that too!

Are you struggling with your sound system?  We have a fix for that as well!

Having problems with your rectangle shaped church?  We have a solution for that!

Having problems with you round church?  We have a fix for that!

Having problems with you octagon church?  We know how to fix those too!

Having problems with your fan-shaped, oval-shaped or square church?  We have custom solutions just for you!

Are you not happy with your commercial warehouse, storefront or converted mall space church?  We know how to fix that!

Have you already fixed your acoustics 9 times before and your still not happy?

We can fix any church that is absent of any acoustical planning and treatment.

We can also diagnose and fix any church that has the wrong acoustical treatment to get it back on track.

We have never been to a church that we couldn’t fix but we have had churches that were not ready to make the needed changes to get what they desperately wanted.  Oh, did you know that acoustics has always been the deciding factor in the aesthetics in a house of worship whether the acoustics are good or bad.  God taught us that beginning with Solomon’s Temple. (1 kings 6:29 (NIV)On the walls all around the temple, in both the inner and outer rooms, he carved cherubim, palm trees and open flowers.  (Please read my article about Solomon’s Temple http://www.jdbsound.com/art/art570.html))

Churches are not temples but they are dedicated as worship centers and houses of learning.  For worship and learning, you need tools. One of those tools is acoustics. You need a system of managing the air between the teacher and listener for the best worship and learning experience.  While a sound system is also a tool it cannot manage the air. It relies on acoustics for it to work. The better the acoustics, the more effective a sound system is.  Without the right acoustics, what are you really hearing or understanding?

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Acoustician vs Architects

Posted by jdbsound on June 11, 2012

Who gets the final say in Church Aesthetics?  The Architect or the Acoustician?

My opinion suggests that if the Architect is able to provide a space with the right acoustical performance, then they get the final say.  If they fail to design a complete worship space that meets the churches needs acoustical for the life time of the church building, people like me get the final say in how a church looks. (I don’t think many Architects like this and this is why they don’t like hiring me.)  Instead some churches are hiring me instead of Architects for their worship space and HVAC designs.  My services cost less and hiring the Architect for just the engineering and exterior finish of the church (which the community sees every day) costs way less too.

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Kingston Road United Church

Posted by jdbsound on May 25, 2012

Kingston Road United Church.

Location: Kingston Road, Toronto, Ontario Canada

Consulting Date March 2008
Completion Date by Church members – October 2008
Sound System installed by Westbury Sound – December 2008

  1. Seating capacity 500+
  2. Ceiling over 40 ft high
  3. Over 120 Cardboard Tubes custom made order and placed around the room in 8″ 12″ and 16″ half rounds.
  4. Between 120 to 800 hertz removed 18 to 22dB of excess energy.
  5. This change allowed a single speaker system to cover a whole room 134 ft long.
  6. Throw distances from speakers to back wall, 98 ft.
  7. Contractor who installed the system was surprised at how well this sound system worked and how much the room changed.
  8. Contractor suggested delayed speakers before the acoustical treatment was done.

If you wish to see additional photos of this project, visit my Flickr Photo Library.   Use this link to see them.   https://www.flickr.com/photos/jdbsound/sets/72157607243842820/

 

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Finished Churches

Posted by jdbsound on May 22, 2012

Is a New Church or existing Church complete after it opens for worship or after it has the proper acoustics installed?

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Excess Noise At the Pulpit or Altar or preaching area

Posted by jdbsound on May 22, 2012

When standing at the pulpit at your church and the sound system is off, do you speaker louder or quieter?
When you turn the sound system on, do you speak just as loud or quieter?
If you answer quieter to either of these two questions, you most likely have a major acoustical problem.  Why?

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Natural Acoustical Amplifiers

Posted by jdbsound on May 22, 2012

Walls are amplifiers of sound.
Outdoors – when you double the energy with amplifiers or speakers the sound levels increases 3dB.
Indoors – when you double the energy with amplifiers or speakers the sound level of certain frequencies can increase up to 9dB or cancel the sound 100%.

Example Below:

Armeanian Pentecotal Church Montreal

Before acoustical treatment, there would be 1dB loss at 10 ft and 2dB loss at 40 ft. without the sound system.

After acoustical treatment, there is 4dB loss at 10ft and 8dB loss at 40 ft. without the sound system.  Also, intelligibility changed from 79% at 40 ft to 92% after acoustical changes.  When you add the sound system the coverage with +/-3dB

This was in the middle of the acoustical transformation

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