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Posts Tagged ‘religion’

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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Where are the Carboard Tubes

Posted by jdbsound on August 28, 2017

Churches use a lot of Cardboard Tubes in acoustical room fixes because they are very effective in getting the room performance they want and need.  Cardboard Tube not only outperform all other acoustical products in churches but they are also the most affordable.  There is nothing that can do what half round tubes can do, even at 40 times the cost.

Ok then, what if you don’t like the look of cardboard tubes around your worship space.  Here is an option some churches have been willing to spend a little extra for.

image10

These look like standard 5 inch deep absorbing panels.  They are not.  These are Sono Tubes mounted in a wooden frame and covered with cloth.

image9

The cloth was an added expense and it was worth it.  The fire rated cloth is expensive and before covering the panels, you want to make sure the acoustical system is going to work and work it did.  The church is very happy with the results and they are enjoying the room.

image8

This is what the installation looked like before it was covered.  The wooden frame has no effect on the performance of the half round tubes.  The cloth only affects frequencies above 10,000 Hertz which means they have no effect on speech or music.  In this installation three sizes of tubes were used.

image7

At the bottom is a huge video wall screen.  On the wall are the Sono Tubes.  Yes, the tubes will work behind a vinyl screen.  If you notice the pattern of the diffusers on the wall. that pattern was needed to control lower mids and bass sound energy.  This pattern was pretested in our test room.

northside church video wall

Here is the finished installation of the video system.  It takes three projectors for each screen.  The centre screen is a video wall.

Photos courtesy of Frederic Lachance of Northside Church in Coquitlam BC, 2017.

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Church Ceiling Height Chart

Posted by jdbsound on May 26, 2017

Churches these days are building lower and lower building.  I guess when so many churches have experienced only poor quality acoustics, many wonder what is the point of building a taller worship space.  As it turns out, existing worship space acoustics is doing fine and a lot of churches are are getting their acoustics fixed, sounding better today than they ever did before.

When a church builds a low ceiling, it limits congregational singing and it makes you more dependant on technology, but guess what!  The same things that limits congregational singing is what also limits the performance of all sound systems.  So, instead of getting 100% out of your high quality over priced expensive sound system, your getting only 40 to 60% of the sound systems true performance abilities.  It is actually cheaper to build higher than the added cost of audio technology to make up the difference.   The chart below should clear the air as to the minimum height your next church should be.  Also, a taller worship space does not mean being stuck with longer reverb times. A higher ceiling means natural room reverberation is adjustable and tuneable.  With a taller ceiling you can change the frequency response of the whole room without needing a sound system or equalizer.

Minimum Church Ceiling height Chart.JPG

Church height is important for a worship space.  One of the biggest parts of worship is singing.  Congregational singing to be specific.  When singing as a group, several elements are required for a good and healthy worship experience.  There is chorusing, harmony, sound volume or loudness of the singing and being able to hear yourself as well as the people around you.  When all of these elements are in balance, the worship experience is like no other.  The majority of people get a lot of satisfaction from the singing experience during worshiping in rooms that have ceiling heights that matches the size of the seating capacity of the worship space. The above chart are minimum heights.  If you want to build higher, you can as the singing experience gets even better but the improvement is more subtle.
High ceilings allow better and less expensive sound systems to be used.  Higher ceiling permit better gain before feedback and it becomes easier to isolate drums and floor monitor. The performance of the sound system is much better too when that is coupled with a good quality acoustical management system.
There are economic advantages too.  The higher the ceiling, the cheaper it is to heat and cool when using a vertical displacement HVAC type system which is specifically designed for large gathering spaces for people.  Such systems cost less to install, they use smaller HVAC components and cost about 30 to 40% less to operate.  In addition, the cooling systems last 2 to 3 times longer before needing to be replaced.
Another thing to consider. If building new, don’t build a flat ceiling that is parallel to the floor. (and it doesn’t count of you put in a sloping floor.)  Many churches that are moving into commercial buildings are learning the hard way that flat ceilings limit the quality of live musical performances and congregational singing.  Sure, there are acoustical panels that can slightly improve the room for amplified sound, but the cost doesn’t justify the returns.  There is little that can help congregational singing even if you have the height. Vertical standing waves are hard to manage than horizontal standing wave. If you know what you are doing, horizontal standing waves can be controlled to create an outstanding room.  It is part of the formula for the almost perfect worship space.  Funny though, most concert musicians that perform in a church that I have fixed, they often make comments like, “I wish our concert hall sounded and performed as well.”  That is almost like saying, “concert halls make for lousy worship space but worship spaces can perform better than a concert hall.”
*Note* In any country that has freedom of religion laws, the worship space portion of a church building has no roof heights limits regardless of local city building height restrictions. 

**Note** The data is based on 2800 churches from North America, Europe, Philippines and Central America. 

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Social Media

Posted by jdbsound on November 5, 2012

Is Social Media and Sermons on YouTube or Web Streaming replacing the need for good sounding worship spaces?

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