Are You Overlooking Acoustic Finishes in Your Design?
- Jan 30, 2020
Acoustic finishes may not be what you think. Are you overlooking them for your projects?
As acousticians, we are used to defining reverberation time (RT) for our clients and colleagues quite frequently. For those that don’t know, reverberation time is the time (in seconds) that it takes sound to decay 60 decibels from its original level within the 500 Hz octave band frequency.
Typically, Long reverberation times can result in a buildup of overall sound energy, creating a very harsh and cacophonous environment, especially in large occupied spaces. Excessive reverberation and sound build-up must be avoided to provide comfortable conditions for those within the space. Suitable reverberation times are determined based on the function of a space.
Acoustic finishes can be used to control a given space’s reverberation time, and can easily be incorporated within your designs. More often than not, in spaces where speech intelligibility or group activities are hosted, the reverberation time of a room is too long and must be shortened. Incorporating acoustic finishes in scenarios like this are one of the most effective approaches to remedying long reverberation times.
In architectural acoustics, we like to consider two main elements when incorporating acoustic finishes into our project:
Almost every acoustic finish and material is given an NRC value (ranging from 0.00 to 1.00) based on its average absorption performance data across the spectrum. Typically, the higher the NRC value, the better. However, it is important to note that while the NRC value provides an average of the absorption across a frequency range, it can be misleading in terms of its absorption at specific frequencies. For instance, perforated wood products are known to perform well at some frequencies and not so well at others.
Keep in mind that the NRC value of a given finish material is dependent on how it is mounted to the ceiling or wall! Some product performance ratings assume that there is to be an airspace – sometimes a significant one – behind the finish.
Aesthetics are a huge component of design projects. Because of this, its an important element to consider when deciding upon acoustic finishes and how best to incorporate into a given space. In the past, acoustical finishes have gotten a bad rap for being bulky, not aesthetically pleasing, or just outright ugly. Traditionally, the approach for reducing long reverberation times was to utilize acoustic paneling for walls, acoustic tiles on ceilings, or carpeting on floor. While these traditional solutions can be effective, they do not always fit in within modern space designs.
Nowadays, there are many different solutions for spaces when it comes to acoustic finishes that should not be overlooked. These sound absorptive materials can include faux-concrete, acoustical plaster, and even brick-like, wood, and/or perforated metal materials. Faux-concrete and plaster products use fiberglass sheets to give the same appearance as concrete, while maintaining those absorptive properties that allow for better acoustic performance. Depending on the project at hand and its acoustic intent, acoustic finishes can be selected in order to balance the visual and aural experiences.
As acoustics designers, we set out to make our design team’s vision not only become a reality, but to function. We work collaboratively to maintain the artfully-crafted vision of our team, while also meeting the acoustic needs of a space for a well-rounded design.