Church Acoustics & Sound Systems

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Posts Tagged ‘Sound Pressure’

The Scientific Foreknowledge the Bible Teaches about Church Sound?

Posted by jdbsound on July 26, 2019

Here is a fresh look at Solomon’s Temple and how it relates to Modern Churches today. Here is link to a 13 page article about church acoustics from the Bible’s point of view.
The Scientific Foreknowledge the Bible Teaches about Sound and Acoustics?

Introduction

The quality of church worship is critical to the health of a church.  The better the excellence of worship is, the stronger the church will be.  Quality of worship is not about packing the church full of people for the sake of filling a worship space so much that it becomes necessary to keep building bigger buildings.  We worship God, not buildings or pastors or knowledge.  It is the Gospel, the Bible that leads us to God.  It is God’s words that keep us in a relationship with Him.  The strength of a church is not measured in numbers in the seats or money.  Jesus taught us to feed the hungry, clothe the poor, and shelter the homeless.  The Bible teaches over and over again that we are to live by example (Psalms 1:1-6), to be a light in the world (Matt 5:16), when they see that we are different (James 2:14-26), it will be that difference that will attract people to God.

The strength of a church is measured by how people support each other, and by how much a congregation supports each other as a family first, as brothers and sisters, and then the local community.  Is the church feeding the hungry, clothing the poor, and sheltering the homeless?  The modern version of Jesus teaching for us in countries with a democracy and wealth should look like this.  Is the church cutting lawns, clearing driveways, cleaning people’s homes, fixing up members and non-members homes?  How often are church members spending time with the widows, the singles who have never had a partner, or the elderly?  Are these not the things included in what Jesus told us to do?  Are not these the same teachings in the Old Testament?  This is just a small sample of how Christianity should look like to the secular world.

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After reading the full article, please comment on it. We want to get this right as the church community needs this knowledge. If you have any questions, want to learn more or see a presentation about Solomon’s Temple and the Modern Church, contact me here – jdb@jdbsound.com

You church may be one of those that has great sound for all parts of the worship service. If it is, you should let everyone know as it will help to bring more people in. You should let us know so we can tell others. If you find this article helpful, please pass it on. Pass it on to your pastor, your friends and family. Give them the chance to learn what God can do for them today!

Thank you.

All modern churches can benefit from Biblical Acoustics
All older churches can benefit from Biblical Acoustics

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Seeking the Truth

Posted by jdbsound on July 18, 2019

As an expert in Church Acoustics and in the pursuit of the truth, I have also been passionate about finding ways for all churches to afford an acoustical solution that will solve just about every sound problem most churches run into. What can be more exciting than knowing that the cheapest and best acoustical solution in the world for all churches comes from the book that all Christians follow and obey – the Bible. When a church uses the Bible’s method for acoustical management, sound problems almost all go away and in most cases, a sustained higher church attendance happens after around 18 months. God is the author of Church Acoustics and it is time for churches to seek God first for answers and God will reveal His way to solve sound problems in His Houses of Worship. Whenever a church is dedicated to God, doesn’t it become His House?

Joh_14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me. If we take that a step further, Jesus was present in the design of Solomon’s Temple. While Millions have already been saved in the past, present and hopefully the future, how many more can be added if all Houses of Worship were built or brought up to the same acoustical standards as in Solomon’s Temple? Since most churches don’t have that quality of room acoustics, I guess we may never know!

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1 + 1 = 3 or When is Doubling the Power, not +3dB?

Posted by jdbsound on June 17, 2019

Here is a simple test anyone can do to determine the acoustical condition of a church.  Physics says that when the power* is doubled or when doubling the number of speakers, the sound level will increase 3dB.  This result is real when outdoors.  This outcome can be false indoors.  When it is false indoors, it is because there are acoustical problems.  Please notice that it is problems, not a problem.  When adding a second speaker failing to increase the sound 3dB, this test shows that it is never a single acoustical issue.  It is not a sound system problem.  The sound system is exposing the root problem. (If the second speaker is wired out of phase, the sound will decrease in level.)

Outdoors, sound follows the basic rules of physics.

When outdoors, if there are two loudspeaker playing with the same volume of pink noise side by side or up to 6 feet apart, and set up a test microphone or SPL meter 30 feet away. (An iPad or phone with testing software can be used if it is calibrated.) When the second speaker is turned on or off,  the sound level will change 3dB.  This result is constant in physics.  The reason this is always true is that there are no barriers around to limit the sounds from spreading out or returning from a reflection that can interfere with the direct sound.

When indoors, depending on the size of the room, often this is not true.  This failure is noticed the most with Subs and sound energy below 500 Hertz.  Doing the same test at 30 feet inside of a church, the sound level change is often 1, 1.5, or 2dB.  If the result is 3dB, there are either a lot of open windows, lots of doors that are open, the church has more than 3000 seating or the church has great acoustics. 

Indoors, sound is confronted with many other rules of physics which changes how the first rule works.

Here are the most common reasons for the sound failing to increase 3dB when doubling the power or speakers.

  • Standing waves
  • Dimensions of the room
  • Too much-stored energy in the corners
  • Too much high-frequency absorption

Standing Waves

Standing waves are excessive amounts of energy between parallel walls within a confined space.  It can often hear it.  To listen to it in a rectangle room, go between the parallels walls that are the closest together. Often it is the side walls.  Stand about 4 feet from one of the side walls.  Make a loud, sharp noise like a hand clap once.  If a person hears any rapid pinging sounds, this is a sign of standing waves.  The sound heard is often a higher range of frequencies, and they usually called flutter echoes.  Flutter echoes are a symptom of standing waves.  Bass sounds, which have longer wavelengths can’t produce the same volume of sound to hear as a flutter between parallel walls.  Whenever a person hears flutter echoes, excess bass energy present too.  This result is also true for all other room shapes when flutter echoes or flutters from a simple hand clap occur.

A second clue to standing waves is when standing at a pulpit or where a minister preaches from. With a hand clap, if the reflected sounds are coming from the side walls or behind standing waves are the cause of it.  The standing waves are preventing a large portion of the sound from reaching the other side of the room, and what is reflected back is being canceled out by the standing waves a second time which in turn prevents people from hearing the clapping returning from the back of the room. Standing waves have the effect of isolating everyone from each other in the room.  This result is also why the drummer seems to sound so loud and why most drummers strike the drums harder than they have too. It is because they can’t hear their drums at a lower level.  This outcome is also why many people comment that they can’t hear themselves when singing, and it makes them feel alone in a room full of people.

Any church with parallel walls will have standing waves if there is nothing to manage them

The reason the sound doesn’t increase 3dB when adding a second loudspeaker is because of the excess bass energy created by the standing waves in the worship space.  The excess air pressure is like putting a finger lightly on the woofer.  The excess air pressure acts as an acoustical load on the woofer, and that dampens the amount of sound coming from the loudspeaker.

Standing waves can only be removed with diffusion or some form of sound scattering. 

If people try to use absorption to fix this problem, while it will remove the flutter or in some cases, shift the flutters to a lower frequency, the untreated bass energy will make the standing wave problem more pronounced.  It will increase the feeling loneliness and discourage the congregation from singing even more.

The dimensions of the room

In churches with low ceilings or seating less than 200 people, the room is too small to be free from surface related sound inference reflections.  In a larger church space with a flat ceiling less than 16 feet high, the room will have standing waves floor to ceiling which limits the ability to increase sound 3dB with just doubling the speakers.

The reason the sound doesn’t increase 3dB when adding a second loudspeaker is that the room is limiting how much the space can support.  The excess air pressure from the extra speaker is like putting a finger lightly on the woofer.  The excess air pressure acts as an acoustical load on the woofer, and that dampens the amount of sound coming from the loudspeaker.

The only option is to diffuse all of the room if a small church.  If a low ceiling, diffusers will have to be added to the ceiling.  Acoustical tiles and drop ceilings cannot correct this issue.

Too much-stored energy in the corners

Another principal of physic is how sound is affected by boundaries.  A loudspeaker on a 10-foot pole measures 60dB.  We call that free space.  When we put the speaker on the ground, the speaker will be 6dB louder.  That is referred to as “half space.”  When we add a wall and the floor, we call that “1/4er space” and the sound increases 12dB or doubles in loudness.  When we add a second wall to the floor and create a corner, that is “1/8th space,” and the sound rises 18dB. 

Corners collect the air pressure that is created by longer wavelength sounds that accumulate on the flat surface of the wall.  With nothing to direct the sound, the sound pressure moves in all directions.  Eventually, the excess bass energy makes its way to the corners.  Depending on a lot of variables, the amount of energy that builds up is often too much.  Churches will low ceilings, large flat walls, or flat ceilings tend to have too much excess bass in the corners.  All other church shapes, except for domes have varying levels of corner issues if not managed.  Excess corn energy has a similar effect as standing waves.  When there is too much bass, it masks the highs.  This, in turn, creates hotspots and coldspots throughout the room. Hotspots and Coldspots are frequency dependent. If the sound level changes are of a narrow range of frequencies, it was most likely found them with instruments.  When a person notices them with their ears,  it means anyone with a hearing problem will miss out on some of what is being said, or what they heard and what was said was different. 

When the front of a church is in the corner, everything is either 18dB louder or 18dB quieter when compared with churches that have the front on an end wall.

The reason the sound doesn’t increase 3dB when adding a second loudspeaker is because of the excess bass energy created by the bare walls in the worship space.  The excess air pressure is like putting a finger lightly on the woofer.  The excess air pressure acts as an acoustical load on the woofer, and that dampens the amount of sound coming from the loudspeaker.

Keeping excess sound out of the corners is best done with diffusion.  It cannot be done with absorption unless the absorbers are as thick as the wavelength of the sound waves.

Too much high-frequency absorption

Sound arrives at our ears as air pressure vibrating at a rapid rate.  The faster the air vibrates, the higher the sound pitch.  The slower the sound vibrates, the lower the pitch. The vibrations are referred to as Hertz.  Sound travel at 1130 feet per second.  At 100 Hertz, a bass sound has the wavelength of just over 11.3 feet.  At 1,000 Hertz the sound waves are 1.13 feet, and at 10,000 Hertz the sound waves are 0.11 feet or 1.3 inches.  

When there is too much absorption in the room, what is left is too much bass. The excess bass masks the highs. 

For most churches, carpeted floors and padded seating is all the absorption needed. When this much absorption is add, the congregational singing is very dull and people have to be super motivated to see more that 20% of the audience singing.

The reason the sound doesn’t increase 3dB when adding a second loudspeaker is because of the excess bass energy created by too much absorption.  The excess air pressure is like putting a finger lightly on the woofer.  The excess air pressure acts as an acoustical load on the woofer, and that dampens the amount of sound coming from the loudspeaker.

The fix for such a problem is by removing the right amount of absorption panels and replace them with diffusers.  Then complete the room by adding more diffusion throughout the sanctuary to correct the frequency response of the room.

These four issues are never a singular issue.  They are often in combinations or can include all four.  Along with these problems, there are often reverberation issues, echoes, excess late reflections, the poor frequency response of the room, and other room problems that have little to do with this simple 3dB test, but they are usually there as well.  These problems can be heard when a person learns what to listen for.  Looking at how sound system is equalized is another clue of room problems.  The issues have the result of the high numbers of the congregation not singing. (In a church with good acoustics, they will often have more than 80% of the congregation singing every they are familiar with.)

Getting two loudspeakers and doing this test is simple and easy to do.  If the sound doesn’t increase 3dB, this means that adding more subs or more speakers into a worship space will not get the expected outcome. For example.  If the goal is to increase the bass in a worship space 3dB, and sound system has only one subwoofer, do this test, If the bass increased only 1.5dB with the second box, then it will take two more speakers just to get a 3dB increase for a total of 4 boxes. Think of the cost of adding three speaker boxes and all of the related hardware required to support that.  An alternative would be to fix the room with diffusion, the gain will be 6 to 10dB of performance without doing anything to the sound system.  It would be equal to adding 8 or 16 subwoofers depending on other acoustical or architectural considerations.  

Science is amazing when appropriately used to provide real solutions. Pseudo-Science or fake data is often used under the disguise of science and can be used to lead churches to false conclusions.  Many experts in audio and acoustics who see the same data, know these problems are present.  If they are not being addressed, it is because they lack the experience in knowing how to solves such issues.  If a person has done this test and the sound system provider or acoustical expert is not addressing these issue, they are not qualified for correcting sound problems in a church.  It’s like asking a Doctor who specializes in kidney problems to do Brain Surgery. What is needed a Brain Surgeon who knows how to fix both the acoustics and to design a proper sound system.

Get the church correctly evaluated before investing in that next sound system.  It can save those responsible a lot of disappointments down the road.  Fixing a room can cost less than replacing a sound system, or it could mean reducing the size of the suggested new sound system.

* Doubling the power required calibrated volume controls or switches to set up correctly as a viable test.

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Singing at 105dBa!

Posted by jdbsound on April 10, 2015

Congregations can sing at 105dBa.  At least that is what they do in churches that I have fixed and that does happen in other churches too, that perform well.  When they do sing that loud, what do you do?  Or, what do you do when the congregation is starting to drown out the sound system?

  1. Keep pushing the sound system to keep up with them.
  2. Keep the sound system at 90dB and let the congregations voices dominate.
  3. Lower the sound system FOH levels so that the congregation can enjoy what they are doing.
  4. Push the sound system to drown out the congregation as always regardless if the sound system is distorting or not.

Please tell us what you do when mixing.

Joseph De Buglio

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