Office complexes of all sizes and shapes rely on meeting rooms for brainstorming, budget discussions, interviews, board meetings and much more. Other than the carpet on the floor (if carpet is present), there is very little to absorb sound. Many modern buildings are constructed of sheetrock and glass, both of which are highly reflective to acoustic energy. Older buildings may be of brick or plasterboard, but often with high wooden ceilings, sometimes exposed steel and, again, glass. If the floors are wooden, composite or marble, the reverberation time can be surprisingly long in relatively small spaces.
Even moderate-sized rooms with carpeted floors designed for as few as 20 people often suffer from poor acoustics, with further degradation as the size of the room increases. While it’s unlikely that intelligibility per se will be an issue unless the room size is quite large, the willingness of people to spend lengthy periods to discuss new ideas or solve corporate problems, and therefore productivity, can suffer significantly when the acoustical conditions are sub-optimal.
Fortunately, there are a number of excellent products available that can readily be installed to solve acoustical problems. Such products take the form of acoustic absorbers (See Photos 1 and 2) and acoustic diffusers (See Photos 3, 4 and 5). Absorbers reduce reflections by absorbing sound energy, which makes the room sound smaller and acoustically “drier” as the effect of absorption reduces the decay time-length and other characteristics of the reverberant field. Absorbers are typically made of molded foam that’s treated to increase the coefficient of absorption, which incidentally is rated in sabins and named after Wallace Sabine, the father of modern acoustics. Available in various thicknesses and colors, these attractive panels can be easily mounted to walls with adhesive or small fasteners, rapidly turning an overly reverberant acoustical environment into a much more intimate acoustic space. One company, Auralex, will even provide a free acoustical analysis of your room when you fill out a simple form and provide a drawing of the room to them.
On the other end of the spectrum, it can often be advantageous to allow some reverberation to remain, so that lecturers sound more authoritive when they’re speaking to groups during training, sales or other presentations. However, the flutter echoes that are created from reflective parallel walls are undesirable and distracting; they are not a desirable form of reverberation. In this scenario — where reverberation is desirable but flutter echoes are not — the diffuser is the answer. Numerous types are available, most often constructed of wood with a randomized surface area that breaks up the reflections rather than absorbing them. This keeps the reflected energy from returning to the opposite wall, and then back again — which is the source of flutter echoes. Because they’re made of wood instead of lightweight foam, they take a little effort to install, but not much more than that of hanging a large picture frame. Diffusers work well on ceiling surfaces and certainly can be combined with absorbers to precisely “tune” the room in a way that’s acoustically optimal for its usage.
The two types of products discussed above are commercially available, easy to install and can aid significantly in improving the business experience.
Ken DeLoria is senior technical editor for Live Sound International and has had a diverse career in pro audio over more than 30 years, including being the founder and owner of Apogee Sound.