Loudspeakers and Room Acoustics

In Uncategorizedby tfwm

The loudspeaker is the final interface between any sound system and the audience. A critical stage in designing a new or improving an existing sound system for a small to medium size house of worship is the choice of the loudspeaker configuration to be used. A successful sound design is an “organic” process which balances the optimization of room acoustics, aesthetics, and sound reinforcement needs of the worship service.

A well designed sound system must accomplish three minimal goals to perform properly. The sound system must a) play loud enough for all to hear, b) disperse sound evenly through the seating area, and c) have the frequency balance to provide intelligible sound to everyone in the audience as well as accommodate the frequency balance needed by the worship service program material.

The selection of loudspeakers and their location is directly dependant on understanding the natural acoustics of the room. As first stated, this process is organic in nature and the intersection of two very distinct disciplines; that of acoustics and electro-acoustics.

Room Acoustics
The acoustical properties of a room, and not the sound system, are the dominant factor in the quality of sound heard by the listeners. It is amazing this obvious fact if often overlooked or quickly glossed over by committees committed to developing an improved sound experience for their congregation.
Focus is too often on the sound system and loudspeakers instead of the ever important natural room acoustics.

A subjective and preliminary room acoustics evaluation can be accomplished by answering a few basic questions. Is the sound understandable when the pastor is speaking? Does music sound natural when the praise band is performing? Are there any echoes or reverberations that are distracting?

The acoustic properties of most small to medium houses of worship are distinctly different from the small spaces most of us are typically familiar with, such as those found in a typical home. These larger, more complex architectures require a level of expertise beyond most of our personal experiences to evaluate and suggest architectural modifications to create a better listening environment.

An acoustic expert (acoustician) will be able to suggest architectural modifications to a room to maximize the quality of any sound in the room, including amplified sound. Recommendations can sometimes be as simple as the addition of acoustic panels to create more sound absorption or diffusion. The acoustician creates a balance of loudness, liveness and reverberation to allow a room’s acoustics to behave uniformly and sound natural.

The acoustic evaluation also will include what external noise contamination may be affecting achievement of good sound in the worship space. Examples are heating and air conditioning systems, traffic noise, and isolation from adjoining rooms and areas.

Once a stable acoustic environment is designed to meet the needs of the worship style, the sound system design or electro-acoustic portion of the project can begin.

The electro-acoustic part of the sound design begins with understanding all of the requirements based on the worship style and other uses of the room. Only then can a loudspeaker configuration be matched to the congregations needs. This critical decision on loudspeaker configuration including locations is guided by program needs and balanced with the acoustic environment and aesthetic concerns.

Basic loudspeaker array configurations typically used include a center cluster (group of carefully aimed loudspeakers), left / right clusters, distributed system and delay systems. A single configuration or combination of configurations can be chosen based on program and aesthetics.

Loudspeakers used in these configurations are application specific with sometimes a half-dozen different kinds of loudspeakers working in various discreet “zones” required to create the proper sound coverage, intelligibility and dynamic range.

Loudspeakers must be seen to be heard. There are numerous ways to blend the loudspeakers into the architecture. This can sometimes be a contentious issue with church staff. Whenever practical, aesthetic concerns should be balanced with the requirement for proper loudspeaker placement.

Portable sound systems, which may have proven to perform well in other rooms, may not be what are called for when it comes to installing loudspeakers. The focus must be on the configuration which best suits the room acoustics and not the name brand or current popularity in the marketplace. Once a loudspeaker configuration and locations are determined, the rest of the sound system including amplification and control can be designed.

Good loudspeaker solutions will not help poor room acoustics and better acoustics will not help optimize a poorly designed loudspeaker system. This holds true regardless of the budget available. The most successful installations include a careful analysis of the acoustics and investing in the necessary architectural changes to allow for the best room sound based on worship style before a sound system is ever turned on.

What we can expect in future
The fundamentals of acoustics never change. What is changing and continues to evolve is the wide variety of amplified material that is expected to sound good in today’s contemporary worship space. From youth services to bible studies and organ recitals it is becoming more and more challenging to create the best sound environment for all needs from a single sound system that is affordable and easy to operate.

Expect to see a continuing evolution of loudspeaker and control system solutions developed to meet these ever demanding needs. Some of these developments will be refinements of existing technologies and design approaches. A major trend will continue to be the integration of amplifiers and digital signal processing directly into the loudspeaker (powered loudspeakers).

The significance of this powered loudspeaker trend will be twofold. Sound systems should become easier and more efficient to setup. Most of the basic pre-engineering will be done by the manufacturer during the design and manufacturing of the product. The second major benefit will be the ease of correct acoustic combining into multiple loudspeaker clusters to create evenly dispersed, coherent sound over large audience areas.

Loudspeaker arrays with digital signal processing and amplification for each loudspeaker have the capacity to allow the implementation of advanced system optimization techniques such as sound beam steering, gain shading and frequency shading which allow a more accurate and natural sound for the entire audience.

These advancements will help continue to refine the best match of sound systems to room acoustics. Additionally these on board electronics when combined with a computer network can assist in real-time reporting of the health of the system, notifying the user when maintenance may be required.

Good Sound
Good sound design is a balance between room acoustics, electro-acoustics and aesthetics. Focusing on any one area without consideration of how it affects the other two is a bad idea. A good design team must not only understand the worship style and needs of the congregation, but carefully consider the acoustic environment in which the design must work and also be sensitive to the aesthetic needs of the congregation as well as budget considerations. This organic balance of room acoustics and electro-acoustics is a constant give and take proposition, but when done with patience, care and the correct expertise, always delivers the best sound.