Myths about Acoustic Ceilings

Acoustic ceilings are often overlooked when designing the ideal office space. In order to achieve a balanced room, it’s important to analyze a room’s dimensions, the number of people using the space and the activities taking place in the room. There are a number of misconceptions surrounding sound design and we’d like to take some time to address these myths and offer some solutions to ensure that you are getting the most out of your acoustic products.

Myth #1: It’s okay to sacrifice ceiling absorption for higher sound blocking.
Truth: Good acoustic design begins with ceiling panels that have a high sound absorption rating.

In the real world of sound building design, effective noise control begins with ceiling panels that have a high sound absorption rating. These panels absorb noise in large open areas and prevent sound from bouncing off of surfaces and causing disruptions in the workplace.

Building standards have changed over the years and now have a reduced permissible reverberation standard, making high performing ceilings (NRC 0.90+) not only recommended, but required. When low performing ceilings are installed, additional sound absorption in the walls and floors are needed, adding unnecessary costs.

For contractors, designers and architects to achieve a successful acoustic experience, they must rely on the high performance of their ceiling panels to achieve acceptable sound absorption ratings. Unfortunately, as customers sort through the variety of ceiling panel solutions, they are often meet with inferior products that degrade the sound absorption strength by trying to provide noise blocking qualities as well. These dual-purpose or multi-functional panels often cause designers to compromise the acoustic integrity of the building causing them to fall short of the required standards needed.

Here are the NRC categories to consider when choosing the optimal absorption for ceilings: Best NRC 0.90; Better NRC 0.80; Good NRC 0.70; Avoid NRC < 0.70.


Myth #2- Ceilings are effective at blocking noise between rooms. CAC (Ceiling Attenuation Class) ratings are an effective measure of sound blocking for ceilings.
Truth: Although ceilings are effective at sound absorption they are not very efficient at sound blocking. In order to properly block noise between rooms it’s important to have the mass of a wall or slab.

In order to effectively block sound, a material or assembly must have enough nonporous mass and be free of penetrations that allow sound to pass through it. Traditional, lightweight modular acoustic ceiling panels do not have the mass necessary to block sound effectively. Ceiling systems have significant flanking paths – or noise leaks – created by light fixtures and air devices that weaken their sound block qualities.

Therefore, the Ceiling Attenuation Class (CAC) of ceiling panels, does not effectively account for these conditions and cannot be viewed as an accurate measure of what will be experienced by occupants of the building. Using the CAC value of a ceiling as a performance indicator to block noise is the wrong sound design approach.

It’s important to use slabs and walls in conjunction with acoustic ceiling panels to offer a complete sound absorption and blocking package. Understanding the differences in characteristics between ceilings and walls will help you become more effective at sound design for your next construction project.

The ability of walls to block sound is commonly specified at levels 10 to 20 dB higher than what common, modular, acoustic ceilings of any type can achieve. Blocking categories for walls are: Best STC 50+; Better STC 45; Good STC ; Avoid STC < 40.


Myth #3- High performance acoustic ceiling systems are too expensive and don’t add enough value to an office.
Truth: After factoring in the decrease of material waste, 25% labor cost reduction, and a productive staff working in a quiet, properly sound designed office it becomes clear that proper acoustic ceiling systems are actually cost effective and necessary for success.

Today’s trend to provide open space areas for employees can compromise their ability to speak with customers on the phone or with colleagues to complete their everyday tasks effectively. This reduction in productivity result in longer project timelines and unhappy clients. By designing a space that effectively absorbs and blocks sound, staff will be able to work more efficiently saving money on overtime and additional resources.

Additionally, since Rockfon® stone wool products are easy to cut and have robust edges, they result in less waste and neat, efficient installations. Rockfon® solutions are less brittle than other materials making them less prone to damage. Also because of the usability of the product companies save an average of 25% on labor costs.

In summary, remember that ceiling panels work best at absorbing sound, and walls work best at blocking it. Using each effectively can achieve a productive work environment and save you money.

For more information about acoustic ceiling and wall products, contact Merrimack Building Supply at or call 800-715-7001.

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