Dispelling The Myths of The Role Flooring Plays in Room Acoustics

Acoustics has become a factor of ever-increasing importance in modern construction. Acoustics plays an important role in nearly every sector of the market in the healthcare, education, residential housing or other industries.

Room acoustics basics
Sound energy can be generated in two ways: through the air and/or building structure. Once sound energy is airborne or structure-borne in a building, it interacts with the surrounding floor, walls and ceiling. At each boundary, portions of the sound energy are reflected back into the room, absorbed on contact with surfaces or transmitted to adjacent spaces. The surface materials and room construction determine how the sound energy propagates. Specific metrics—such as Noise Reduction Coefficient (NRC), Sound Transmission Class (STC) and Impact Insulation Class (IIC)—have been developed to quantify these properties.

Surface absorption
NRC is a single number metric used to represent the average absorption of a surface across the central range of speech, which is generally at a frequency between 250 to 2,000 hertz.

STC is a single number metric used to quantify the transmission capabilities primarily of a wall or flooring assembly, based on Transmission Loss (TL) values from 125 to 4,000 hertz.

The IIC metric was created to quantify the impact sound insulation capabilities of a floor assembly.

Industry segments
• Healthcare: In hospitals and doctors’ offices, the most prevalent surfaces are hard, sealed floors due to their many inherent benefits.
• Education: As with the healthcare industry, most floorings found in schools are hard, resilient surfaces for functionality and durability purposes.
• Office: Unlike the healthcare and education industries, carpet has been a trend in the office segment for several years.
• Residential: Single residential homes are not generally concerned with having high STC, IIC or enough acoustic absorption, except in large volume atriums or similar spaces. Room furnishings often provide enough absorption.

Choosing the correct flooring solution
• Acoustic goals: Among the first questions that must be answered are: What are the acoustic goals of the space? Is there significant noise? How quiet does it need to be? Are there specific requirements for reverberation time or other acoustic metrics that must be adhered to? Would acoustical treatment be useful, feasible or financially justifiable?
• Building layout: If a building includes a particularly noise-sensitive space, the location of that space should be placed to minimise sound transmission from interior or exterior noise sources.
• Building construction: The type of construction determines many acoustical parameters, including STC and IIC. A structure built using concrete slab will exhibit different acoustical strengths and weaknesses compared to steel or wood.
• Acoustical treatments: Using absorptive acoustical treatments to reduce reverberation and increase speech intelligibility within a space is more efficiently met by applying acoustical wall and ceiling treatments, rather than flooring solutions.

In summary, the absorption and transmission of sound energy in a built environment is impacted by the type of construction and building materials selected, and this is true for flooring. The greatest impact flooring has on the acoustic environment is related to the transmission of impact noise (IIC), but it has lesser influence on the transmission of airborne noise (STC) as those characteristics are more dependent on the construction of the subfloor. Flooring is also not an efficient way to deal with absorption of sound within spaces (NRC), compared with acoustic wall and ceiling treatments.

Careful consideration of the acoustic goals for your building spaces is essential prior to making construction and material selections, and flooring does have a role in achieving optimum indoor environmental quality for building occupants—just not a major one.

Source: White paper written by Jay Bliefnick and Dr Lily Wang of the University of Nebraska–Lincoln وان ایکس بت بت فوروارد