In order to effectively block sound, a material or system must have enough mass and be free of penetrations which allow sound to freely pass through it. The reality is, traditional, lightweight modular acoustic ceilings by themselves simply do not have enough mass to block sound compared to other building components, such as walls. Ceiling systems will always have substantial flanking paths – or noise leaks – created by installing light fixtures and air devices, among others – which make them even less effective at blocking sound. At the end of the day, the way Ceiling Attenuation Class (CAC) of ceiling panels is tested, does not properly account for these conditions and cannot be viewed as an accurate measure of what will be experienced by people in buildings. Using a ceiling alone to block noise and using CAC values as a performance indicator is the wrong design approach. That’s why you will not see CAC as a performance metric in acoustic standards, guidelines and rating systems.
What is the real solution? When it comes to ceiling systems, absorption is the most important attribute for overall noise control. Designers should start by considering how each room will be used and how sensitive occupants may be to noise. Is the focus of the space meant for conversation in education settings, concentration for office spaces, or relaxation or sleep in hospitals and care facilities? Without carpeting or space for wall-mounted sound absorption, the solution lies in high-performance, sound-absorbing ceiling panels with a Noise Reduction Coefficient (NRC) rating of 0.90 or higher. After absorption is optimized, designers can then choose from a variety of options to effectively block sound if and where it’s needed. This includes the use of walls and plenum barriers, proven to be the most effective architectural components for reducing sound transmission between rooms and compliance with the acoustic requirements in industry standards.