2. Space experience and how occupants “listen”
How do the acoustical characteristics of a space affect the listener’s experience? We listen with our brain, not our ears. The ears receive the sound pressure wave and transmit the information to the brain for interpretation. Based on copious amounts of information contained in the sound pressure wave, the brain tells the listener where the sound is coming from (directionality), how large or small the room is (reverberation time) and the tonal quality of the sound source. That said, every surface and element in the room has an effect on what the brain interprets.
Too much absorption in a space will reduce the reverberation—and the brain will perceive the space to be small. Too little absorption (increased reverberation), and the brain perceives the space as large. In other words, the room’s cubic volume and the reverberation time should match so the room sounds the same as it looks. 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.3. Balance is everything
A third tenet an architect should take into account when designing a space is to achieve an acoustical balance—so the space sounds the same size as the room’s physical size. Too often, spaces suffer from an acoustical imbalance; they sound two-dimensional. This is common when the floor is fully carpeted and the walls and ceiling are hard surfaces. The floor is absorptive and the walls and ceiling are reflective. What’s worst is when the floor and ceiling are both absorptive and the walls are flat, reflective and parallel. Almost all reverberation (energy) is in the horizontal plane (side to side) with no auditory clues perceived from the floor or ceiling. The brain does not perceive a floor or ceiling’s presence due to inaudible clues.
What can be implemented to create a well-behaved space or fix an acoustically challenged space? The short answer is to study the space rather than just throwing treatment in it. Determine the purpose (use) of the space, identify a reverberation target then calculate the room’s reverberation time (RT) based on the finishes. A healthy acoustical balance is the goal.
Acoustical treatment can be grouped into absorption and diffusion categories. The most common absorption panel (adiabatic) is compressed fiberglass wrapped with porous fabric. These panels are most effective for absorbing mid and high frequency. Adiabatic absorbers are the most common type of acoustical products used to lower a room’s reverberation time and control reflections.