Although each project is different, the general procedure for preparing an acoustical design is usually the same. The acoustician, professional or not, usually begins with the blueprints or other drawings of the room; it might be new construction or an existing room. The acoustician must determine exactly how the room will be used; this is often difficult because many diverse demands may be made on a room. Because noise intrusion is usually a concern, a noise survey of the site is often undertaken. Based on the acoustician’s analysis, the goals of the acoustical design are decided. Then, based on the size and shape of the room, building materials, and other factors, a design is prepared and integrated with the overall architectural design. Because of budget, taste, or some other necessity, plans are often modified many times before construction is completed. Clearly, it is best to finalize a design before construction begins, but this is often not possible and running changes are usually inevitable.
During the design phase, blueprints form the basis of the discussion and allow the designer to literally visualize and explore ideas and to share them with others. As a building is constructed, it is the blueprints that inform and guide the builders during the construction process. Good blueprints give builders the essential information they need including building materials, fabrication methods, and dimensions. The blueprints supplement the written contract signed between client and builder and allow verification that the work was done properly or at least according to the specifications stated in the blueprints. Moreover, blueprints document the work that has been done and serve as future reference. This record is invaluable during upgrades and renovations.
After construction is completed, the room’s acoustical characteristics can be objectively and subjectively evaluated. In many cases, some treatment can be adjusted to optimize results. In some cases, some parts of the construction can be left unfinished pending final evaluation. For example, a room can be preliminarily left with deficient absorption, and then absorption can be added as necessary to achieve the desired reverberation time. It is easier and cheaper to add absorption rather than take it away. Similarly, other modifications can be made to a “finished” design to further optimize the acoustics. As noted, it should be remembered that furnishings and people will also affect a room’s acoustics.
Acousticians are often asked the question—what is good sound? We will explore ways to objectively and subjectively evaluate room acoustics in later chapters, but it’s worth nothing that acoustical design is certainly not a “one size fits all” situation. Different rooms require very different kinds of acoustical characteristics, and even rooms used for the same purpose can have different acoustics, and still have good sound. For example, many concert halls are admired for their fine
acoustics, yet they all sound distinctly different. In fact, part of the pleasure of acoustics is hearing and appreciating these differences. In addition, listeners have different tastes and come from different cultures, and thus may have very different opinions on what the optimal sound should be. On the other hand, there is usually no disagreement when it comes to poor acoustics; it is usually apparent when speech is unintelligible, when music does not sound full and rich, or when intrusive outside noises are hear d.
There is no simple solution to the design problem, but ultimately it is the duty of acousticians to reconcile many different and sometimes contradictory criteria, and to make sure their room designs provide a consensus “good sound.” Acoustical design is an art and a science. It has theoretical roots in physics, material science, and psycho-acoustics, but many subtle aspects of acoustical design cannot be easily explained by theory. Good acousticians acquire a feel for expert design that comes from years of practical experience.