Acoustics First: Sound design as more than an afterthought

Figure 3: Drywall with a high-density core allows for enhanced acoustical performance.
Image courtesy CertainTeed

As with the healthcare industry, most flooring found in schools possesses hard, resilient surfaces that enhance functionality and durability. However, carpeting can be installed in specific spaces to reduce impact noise from sources such as chairs scraping against floors. Classrooms, for example, generally require lower background noise levels and lower reverberation times to ensure students can clearly hear instructors. Absorptive materials with high noise reduction coefficients (NRCs) are effective when placed on the ceiling or upper wall.

“Most classroom settings require complete auditory solutions that pertain to flooring as well as the walls and ceiling assemblies,” says Robert Marshall, an expert in ceilings. “There are high-performance ceiling panels available, such as fine-fissured mineral fiber solutions, that not only meet rigorous acoustical standards, but exceed them within the ceiling category alone.”

Carpet, walls, ceiling tiles, and partitions can be installed to address unwanted sound. In an office, the main distracters are ‘people sounds’ like phone conversations, throat clearing, and vacuum cleaners, but can include anything that could distract a listener.

Walls are especially critical in open-concept offices, where meeting rooms are necessary to block and/or absorb unwanted noise. Walls serve as the enclosure of a space—thus, the installation of acoustically rated drywall products specifically designed to provide mass to the system can disguise unwanted noise and increase levels of privacy when needed (Figure 3).

“Advanced drywall products with inner layers of viscoelastic polymer help dampen vibrations by creating a shock-like absorber within the structure of the wall. This type of ‘constrained layer damping’ performs well acoustically over an extended range of frequencies, resulting in increased STC ratings for the systems,” says Lucas Hamilton, a gypsum wallboard expert.

Regular, predictable background sounds, like an HVAC system, are easier to block out than disruptive sounds, like conversation over a cubicle wall.

“However, HVAC system sounds can also be addressed with rotary duct liner insulation,” says Hamilton. “A key benefit of insulating a duct on the inside is that the insulation provides noise reduction, in addition to maintaining the temperature of conditioned air that passes through it. Furthermore, when ceiling tiles, which are highly absorptive, are used in conjunction with other highly absorptive products like flooring, insulation, drywall and partitions, they can play an essential role in office acoustics.”

However, mechanical system sounds can also be addressed with rotary duct liner insulation. This not only moderates the temperature of the air passing through the HVAC system, but also reduces noise—particularly effective when used in conjunction with flooring, drywall, partitions, and other types of insulation.

As employers continue to renovate and build open office spaces, employees are voicing concerns about their abilities to work productively in what they anticipate will be a noisier, more distracting workplace. The overwhelming complaint about open-plan office design is the lack of acoustic privacy. (For more information, consult the Springer Handbook of Acoustics, edited by Thomas Rossing and published in 2014.)

Some settings within this environment may call for only visual privacy, but others require both visual and total speech privacy, while end-users in the same space might need normal speech privacy (in which conversations in adjacent areas can be understood, but do not detract from concentration). Proper acoustic design, including furnishings, partitions, and partial walls, can help address these needs while averting serious issues down the line.

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