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Engineering to Enhance Sound

In this first installment of Sound Decisions, we’ll begin with an introduction to acoustics. To some, the subject of acoustics may seem a bit “non-technical.” Yet, acoustical design is a technical discipline. Furthermore, proper sound system design requires understanding the behavior of sound i.e., acoustics.

The relationship between the room and the loudspeakers can be considered the most crucial part of any sound system design. Those who follow the ChurchSoundCheck list-serve know that professionals responding to posted questions about loudspeaker choices or favorites normally preface their remarks by some mention of acoustics. In fact, we at Pelton Marsh Kinsella (PMK) usually refer to our firm first as an acoustical consultancy before adding that we provide design and consulting services in sound reinforcement, video, and lighting systems. The implication – acoustics first!

Since this is our first submission to TFWM, we felt it best to start with the basics. Future discussions of sound reinforcement will account for the acoustical character of the room. Nowhere is this more critical than in performing arts venues and churches. The basic function of a worship space is to convey a message through music and the spoken word. To leave the acoustical performance of a worship space to chance is to invite continual frustration for the life of the building.

We live in a vibration-filled world, surrounded by sound that imparts information and emotion. The essential component of music and language, sound gives clues to where we are and what is happening around us.

Sound is a wave created by vibration, a ripple in air and water, or through the steel beams of a skyscraper’s skeleton. Sound bounces off walls and bends around corners. It can be absorbed like water into a sponge or reflected from a hard surface like light off a mirror. The physical properties of sound allow it to be manipulated and shaped.

Acoustical engineers use the physics of sound to enhance a room used for performing arts so that music sounds lively and speech is intelligible. Applications for acoustical engineering range from preventing sound from entering or leaving a structure, to ensuring the proper functioning of a sound system in an outdoor stadium. Acoustical engineers may be called upon to make sure restaurants or arenas are appropriately boisterous and that a classroom is quiet.

The proper management of sound can be the difference between success and failure in symphony halls, churches, airports, auditoriums, office buildings and entertainment complexes. Every building and outdoor facility can benefit from proper attention to acoustics. Considering the acoustical aspects as early as possible, even before preliminary design and site selection, can prevent costly or irreparable mistakes. Once the seating capacity has been determined, the quality of an auditorium or theatre’s acoustical environment is a major ,if not prime consideration in determining the building’s layout and shape.

Acoustical considerations profoundly affect aspects of design. Factors determining the acoustics of a space include size, background noise, geometry of the walls, floor and ceiling, and the density of the room surfaces. The control of acoustics in a building or room is further complicated by how sound is transmitted, reflected, diffused and absorbed.

Sophisticated instruments for measuring and analyzing sound, along with advanced computer modeling techniques, have expanded the capabilities of acoustical engineering, but the discipline still demands the skills and insight of an artist. Dealing with the human perception of sound requires consideration of factors that often cannot be easily quantified.

The physics of sound enable acoustical engineers to configure a building or room for the desirable acoustical properties. In effect, they “fine tune” a space by shaping the walls, adding acoustical elements and reinforcing natural sound with electronic systems.

Sound occurs whenever something vibrates. The oscillation of the vibrating object, whether a person’s vocal cords, the cone of a loudspeaker or the string of a guitar, creates disturbances, or waves, in a medium. Anything that vibrates will create a sound, even turbulent airflow in a heating-ventilation-air conditioning system.

In a room, sound waves hit walls, ceilings, floors, and even the furniture and people in the room. Some of the sound energy may be absorbed, but much of it will be deflected. A complex system of overlapping waves of different frequencies is present. Outside noise-traffic, low-flying airplanes or even the building’s HVAC system can intrude into the space. Sound behaves differently in a small, enclosed space, such as a classroom, than it does in the open space of an auditorium.

The work of the acoustical engineer consists of controlling and shaping sound waves to fit the purpose of a room or building. Sometimes the job is keeping the sound inside the room; sometimes it is keeping sound out. The acoustical engineer may be called in to ensure proper musical acoustics in a symphony hall, or to provide the best sound possible in a multiple-use building such as a church or school auditorium, where music clarity and speech intelligibility are equally important.

In future editions of this column, we will explore the wide world of technical systems for today’s church. Various consultants in our firm will contribute with their expertise in acoustics (see, I told you it comes first), sound, video, and many other systems used to convey the message. We always welcome comments, questions, suggestions, or a simple “Howdy!” Most of all, we hope you find our column informative and helpful. See you next time!

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