The acoustical characteristics of any room are determined by its architecture. Room architecture consists of room size, room shape and room finishes.

This means that room size, shape and finishes determine the room acoustics.

The first factor affecting room acoustics, room size, is usually determined by the number of seats needed for the room and the layout of those seats. 

The aspect ratio (ratio of the ceiling height to room width to the room length) is also a critical factor in the room’s acoustic functionality. 

Each of these factors should be carefully planned early in the design process to minimize potential acoustical problems.

The second factor in determining the room acoustics is the room shape.

Frequently, rooms are designed in a fan shape with a curved back wall and wrap-around seating. This type of room design generally creates a dramatic and inherent problem when it comes to focusing sound.

When designing a room, plan a room shape that does not include concave or focusing wall or ceiling shapes, parallel wall surfaces, or extremely large continuous surfaces. The room shape should reflect sound into areas that will not create acoustical problems.

With regard to room shape and how sound behaves as it bounces around the room, we want to provide early reflected sound energy to the seating areas and eliminate late reflections that are perceived as an echo. 

Whether sound arrives early or late in time is relative to how long after the direct sound it arrives.

In general, the larger the room, the farther sound has to travel to be reflected, and the later it arrives back at a listener.

The later it arrives back at the listener, the more it sounds like an echo and the more it distracts the listener and causes intelligibility problems.

The third element that determines the room acoustics is the room finishes.  Whether a surface will reflect sound, absorb sound, or reflect it in all different directions (diffuse sound) are all contributing factors to the acoustics.

Since we’re looking for early energy, not late energy, we will generally want the surfaces close to listeners to be hard or reflective and the surfaces far from listeners to be soft or absorptive. This is just the opposite of what happens in most rooms. 

A typical room is designed so absorptive surfaces, such as carpeting and padded pews or chairs, are closest to listeners, while reflective surfaces, such as walls and ceilings, are farthest from listeners.

This creates an environment where there is little early reflected sound energy and excessive late sound energy.

Ideally, we want the surfaces close to the listener to be reflective (for example, hard flooring instead of carpet beneath seats) and the surfaces far away to be more absorptive.  This will create a more acoustically balanced room.

As sound bounces around a room, it is perceived as either reverberation (diffuse sound traveling in all directions) or as discrete reflections. 

The level of reverberation and time it takes the reverberation to decay is one factor in measuring the room acoustics. Another is the level and arrival time of the reflections. 

All of these are determined by the room size, shape, and finishes.

From all this information, it’s apparent that the room architecture really determines the room acoustics.

You can’t fix the acoustics without making changes to the architecture.

Another important piece of puzzle in attaining quality sound at your church is how the sound system interacts with the acoustics of the sanctuary. 

These are two somewhat separate issues, but are directly interrelated in that each one affects the other. 

Ideally, both the acoustics and sound system design take place at the same time and are carefully coordinated.

This approach will minimize the number and severity of unforeseen problems.

There are several sound system design approaches. While some may be better than others, the chosen path should be driven by the program and the room design. 

A newer technique for the main sound system involves multi-channel (left-center-right, or LCR for short) loudspeaker arrangement, which can produce an excellent sound experience.

Note that these systems can be very complex to design and set up, but once they’re up and running are fairly easy to operate and can produce stunning results.

The bottom line is that the sound system design is equally as important as the room acoustics. 

Each one affects the other, mostly in negative ways.  Even the best speaker system in the world will still sound bad in a room with poor acoustics.

Vance Breshears has worked for decades as a system designer and consultant in the professional AV industry, and heads up the California offices of Acoustic Dimensions.

Other Articles By Vance Breshears:
Building Your Worship Center For Quality Acoustics