Posted in education
on May 13, 2014 1:18 pm EDT
Space Behavior: The Effect of Audio and Acoustics
An essay from an acoustics expert -- with three important considerations for architectural designers.
The Rock Church in Miami; images show barrel wall diffusers and acoustical panels.
A challenge some architects face is implementing acoustical elements into the interior design of a space. Most owners face budget challenges. The acoustical designer faces both. Form or function? Can both be achieved when designing a space and still stay in budget? By all means, yes.
A simple test to perform is to close your eyes and listen to the space. Your brain will paint a mental picture of how large or small the room is. Open your eyes and see if they match.
What needs to be considered when designing a space is that the space must acoustically support the programmed use of the room. Anything less renders a dysfunctional space. In other words, spaces should be acoustically well behaved. Too often, performance spaces (worship centers, cathedrals, etc.) are deprived of the proper acoustical tailoring and fall victim to “the audio system will take care of it’” mindset. It is very important to understand that the audio system is at the mercy of the acoustics of the room where it is located. No audio system can compensate for poor room acoustics. The proper mindset should be “acoustics first, then audio.”
Acoustical design is a science art. Sound behaves according to the laws of physics, yet all spaces are not used for the same function. A classroom should render high speech intelligibility (low reverberation) due to its academic purpose, where a recital hall should be musical in nature but not so reverberant that speech intelligibility suffers. Blending the science of sound with the art of acoustics produces a balance that gives way to a well-behaved space.
1. The importance of absorption vs. reflection
When designing a space, an architect should take into account the basic tenet that a space must work acoustically for its planned use. This is achieved, in part, by ensuring a balance of absorptive and reflective surfaces. Every material has acoustical properties—even people. However, it goes much deeper than that. The acoustical properties of a given material can be qualified somewhere between absorptive and reflective. For example, concrete has absorptive properties, be they minute, which are grossly outweighed by its reflective properties. Thus, concrete is classified as a reflective material. Carpet is more absorptive by nature, yet possesses reflective properties in the low-mid frequency range. Common materials are classified as either absorptive or reflective, yet these properties are frequency dependent. When designing a space, architects should steer away from hard parallel surfaces—and implement a balance of absorptive and reflective finishes.