Churches and other places of worship are places where acoustic wall panels and other sound engineering products can be essential to get the most out of the experience. There are often a wide variety of sounds produced by choirs, bands, and sermons for a large, possibly noisy audience, so it is key that everyone can hear what is going on.
Furthermore, acoustic problems in churches are often misdiagnosed. They are blamed on bad sound systems, poor instruments or musicianship, or bad microphones. For example, members of a congregation can complain that they cannot understand or hear the worship leader, or that the musical band cannot hear each other. Other complaints are excessive echoing in the room caused by sound waves reflecting off hard surfaces that impairs hearing and distracts audience members. Acoustic panels in churches can tackle these problems and create a much better aural experience for all parishioners.
An easy way to diagnose these problems in a church is to clap your hands loudly and count how long it takes for the sound to disappear. This is called the concept of reverberation, which is when a sound wave reaches your ear in 0.1 seconds or less after it is first projected. This reverberated sound combines with the original sound to create a prolonged sound wave. A long reverberation time means it takes a longer time for these reverberation sound waves to get absorbed, and as a result, it will contribute more to intelligibility problems. This makes the goal of church acoustic treatment to lower the overall reverberation time and to reduce unwanted echoes.
Another common problem in churches is the fact that both spoken words and music need to be treated. In professional recording studios, the two types of sounds are recorded in different ways using different equipment. Therefore, acoustic treatment methods should take into account these two types of sounds and consider the best materials that should be used for each sound.
Let's Get Into the Science of Church Acoustics
Acoustics is a branch of physics that deals with the properties of sound. The engineering component of acoustics uses the properties of sound waves to solve practical problems, such as enhancing the sound reflections inside an enclosed room. Common places where acoustic treatments such as acoustical panels can help improve room acoustics include large public spaces such as churches, places of worship, concert halls, and university lecture theaters where large gatherings of people are expected.
Basic Properties of Sound Waves
To learn about sound treatments and how acoustical panels can help, a basic understanding of how sound waves travel and reflect off hard surfaces is required.
To start off, the scientific definition of sound is a mechanical disturbance that can travel through any medium such as water or air. It is a longitudinal wave, which means that its periodic vibrations travel in the same direction as the wave’s direction of advancement, similar to how a coiled spring can be stretched and compressed.
Like most waves, such as radio waves and visible light waves, sound waves can be quantified by three basic properties:
- The wavelength refers to the smallest repeating unit or the horizontal length of the sound wave. It can be identified by measuring the distance between two equivalent points on the wave.
- The amplitude of a sound wave is also known as the vertical or height of the wave. It is identified on a graph as the length between the highest and the lowest points on the wave.
- The frequency is measured in hertz, or Hz, and is also known as cycles per second. It is measured as the number of times the sound wave travels within one second, with higher frequencies having faster vibrations to make a higher pitch.
How Sound Travels Inside a Church
Whenever a sound wave is produced, it will spread out in all directions and travel away from the source. The energy disturbance created by the sound wave will travel via the air particles inside the room. As these air particles are pushed and pulled against each other, a sound is created and can be picked up by the cochlea inside the human ear, which then converts these movements into neurological signals to be interpreted by the brain.
Additionally, sound can be reflected or absorbed depending on the type of materials it comes into contact with. For sound to be reflected, a special curved surface in the shape of a parabola is required. This allows the sound waves to be bounced out in a straight line toward a single point such as the audience members sitting in front of a curved stage. In contrast, sound absorption requires the energy of the waves to be absorbed to prevent it from vibrating. This occurs in all mediums, even air which can absorb the energy of sound waves and is the reason why you cannot hear someone calling your name across a large open field without a loudspeaker.
Lastly, diffraction is another phenomenon that can occur as sound waves travel within a room. This involves a change in direction of a wave as it is reflected off a surface and occurs mainly at sharp corners inside a room. The sharper the bend of the corner, the larger the amount of diffraction encountered by the wave. It is a highly useful property and can be used to manipulate the angle of diffraction to disperse the sound waves across large open spaces.
Common Acoustic Treatment Methods in Churches
Once you have diagnosed any acoustic problems, it is time to fix them. There are a number of common acoustic treatment methods and materials to choose from. It is best to learn about them so you can make an informed decision when choosing the right method and material to solve your specific problem.
To start off, treating the inside walls of churches is the most common and easiest way to fix excess reverberation problems. This is because these walls are the first point of contact between the sound waves and church audience. The solution requires the installation of acoustic panels, which are usually rectangular shaped flat panels hung onto the walls or ceilings of a room.
Depending on their design, acoustic panels can:
- reduce noise
- eliminate echoing
- filter sound waves
- improve the general sound quality
Acoustic panels can be made from fiberglass, foam, and other materials and be customized based on specific needs.
To determine how much wall to cover, a good rule to thumb to follow is to look at the total surface area of the interior room and apply acoustic treatment to at least 50% of the surfaces. The distribution pattern of the acoustic panels should also be taken into account during installation. For example, some acoustic panels can absorb more sound waves when placed into a checkerboard pattern instead of a uniform covering. This is caused by the varying wavelength of the sound waves diffracting around the room and is the reason why you should always ask your acoustic panel supplier or a sound engineer for the best distribution pattern to use.
Echoing is another acoustic problem and it can be classified as flutter or slapback. Flutter echoes can be identified by a ringing or hissing sound that reflects off parallel side walls, while slapback echoes can be identified by sound waves returning to the stage area caused by reflections off large and curved surfaces. Both can be treated by the addition of scattering devices throughout the room instead of absorption panels.
In addition, to get the optimum balance of treatment between speech and music, music should be treated first. This means the music sound waves should be turned down compared to speech sound waves, which should be turned up. The difference in these two sound waves can be either enhanced or lowered depending on the type of material that goes into the acoustic wall panels. Repositioning of the loudspeakers may also be required as part of a multi-purpose sound treatment.
Choosing the Right Acoustics Treatment Materials for Your House of Worship
Loads of research has been done on the types of materials and their properties used in acoustics science. These materials, such as acoustic fiberglass panels, are used to enhance sound qualities by reducing resonance as well as to absorb or scatter and redirect sound waves inside a room. They must also adhere to strict fire safety standards in many municipalities and can have different densities and thicknesses. Some common types of materials in churches are glass, wool, and fiberglass. Most can be classified into porous materials, metamaterials, and sonic crystals.
- Porous materials contain pores that can be penetrated by sound waves. This makes them great for diminishing sound waves while not absorbing it completely.
- Metamaterials refer to artificially created materials that contain chemical repeating units that are not found normally in nature. This gives them superior properties compared to natural materials and greater customization on the part of the material engineer.
- Sonic crystals contain rows of wave-scattering surfaces that make great noise barriers as they stop sound waves from propagating.
Lastly, the chosen material should also be matched to the frequency range of the sound waves that are causing the most problems. For example, speech sound waves have a frequency range between 300 Hz to 2000 Hz. So, if you are installing panel treatments to enhance speech intelligibility, you need to ensure the materials you are using will absorb frequencies in the intended regions.
Hopefully this overview of acoustic treatments in churches and places of worship has helped illuminate a path to getting the sound in your space much more enjoyable. It's vital to make sure the message is being heard, and acoustic panels and other treatments can definitely help clarify the sound waves that message is carried on.
Sound wave properties
How sound travels inside a room
Common Acoustic Materials
Reverberation vs Echoes
Common Church Acoustic Problems & How to Fix Them