Although many building designers focus on visual aesthetics, acoustics play a vital role in every building environment. Owners expect homes to be quiet, so they don't hear the neighbors. In a classroom, students are expected to focus and learn without being distracted by sound or unable to hear what the teacher says because of competing noise. In healthcare facilities, quiet not only promotes healing, but privacy is mandated: Patients have the right to private conversations with their healthcare providers. In each of these settings, acoustics is the key to meeting basic owner expectations.

Acoustics 101

Before delving into the topic of acoustic controls, we need to know what we mean by “noise,” “sound,” and “control.”

Simply put, noise is unwanted sound. An air conditioner makes a soft, constant hum in the background. As such, this sound helps mask more objectionable noises, such as intermittent traffic from outside. For most people, sounds that are objectionable typically are:

• loud enough to be uncomfortable.

• intermittent rather than continuous.

Acoustics—the science of controlling sound—is made more challenging by the way people perceive sound. Sound is created by vibrating matter. A person speaks in one room, causing pressure waves to travel through the air like ripples on a pond. When these pressure waves strike the room's walls, ceilings, and floors, some of the sound is reflected back, creating a reverberation that continues to bounce around the room until it loses energy. Some of the sound waves can cause the wall, ceiling, and floor to vibrate. This vibration, in turn, transmits pressure waves on the building assemblies on the other side of the wall. These waves then strike the ears of occupants in the adjacent rooms and are heard, provided the frequency is in the range of 20 to 20,000 cycles per second (Hz), and the occupants have decent, healthy hearing. How much sound is reflected and how much is absorbed depends on the type of surface materials in the room.

A recycled rubber underlayment works with a direct application of most floor finishes, including ceramic tile. Photo courtesy of ECOSilence