Measuring and modeling.
When a room’s acoustics can be established with a high degree of precision, it makes the choice of the sound system’s components—speakers mainly but also subwoofers and any digital signage processing (DSP) used to manage them—easier and better able to match the sonic characteristics of the room. The most effective way to do that is by measuring the space, either with the use of software that can measure the acoustical properties of an existing room, or virtually modeling those of a planned space. In either case, software is used to measure key parameters, including frequency response (measured within the range of human hearing, from 20 Hz to 20 kHz, which indicates how the room is responding to various frequencies, looking for peaks or troughs that show reinforcement or cancellation at specific frequencies), and reverb time (RT-60—the time that it takes a sound to decay 60 dB—is used as a baseline). Software, such as SMAART or EASE, is used to interpret the acoustical mapping of rooms using calibrated microphones.
In the case of virtual spaces, predictive models of how environments of certain dimensions and compositions are derived from existing data, also known as auralization, which creates 3D renderings of rooms, and can be remarkably accurate. The room’s physical measurements are transferred from the architectural CAD software into virtualization software, such as CATT or Bastian, and known responses of different types of sound to various types of spaces and surfaces are applied.
Central Synagogue in NYC. Courtesy of John Storyk.
Data, however, are only as good as the analysis applied to them, and that’s where the role of the acoustician comes into play. Understandably, acousticians endorse the idea of using acousticians on all sound system projects. Storyk goes so far as to say that ideally the acoustician and the system designer are one and the same (the company, at least, if not the person). All good ideas— and even if engaging an acoustician in the process increases the initial cost, it may reduce the long-term costs by avoiding bad product decisions that compel replacement of certain system components if they prove inappropriate for the space. (Recall Genfan’s comments about how much remedial work he does.) Keep in mind, also, that acousticians can take into account a wide range of sonic issues around a sound system, such as how HVAC noise can affect the performance of a sound system.
That said, in recent years greater numbers of audio systems designers have become significantly more adept at addressing acoustical aspects of system design. Naturally, some are more knowledgeable about the nuances of acoustics than others; as always, recommendations from your colleagues are key in making choices if you choose to rely on the systems designer for acoustical guidance. But there are some certifications that can also add some reassurance, such as from the Institute of Noise Control Engineering (INCE-USA) in Springfield, Ill. In addition, measurement and analysis tools have become more precise, more affordable, and more accessible, both in terms of cost and ease of use. That will give systems designers more capability to acknowledge acoustical measurement and treatment in their own designs.
That, of course, won’t take the place of what a qualified acoustician can bring to a sound system project, and as the scope of a project grows in scale and cost, so does the importance of having that kind of knowledge in the mix.