A well tried method which has been used over a long period of time for the acoustical design of a bespoke home cinema system is to build a smaller model of the cinema room, under consideration which is similar to the original room, at least geometrically, and to study the propagation of waves in this model. This method has the advantage that, with little expenditure, a great number of variations can be tried out: from the choice of various acoustic wall treatments to major changes in the shape of the home cinema room.
Since several properties of propagation are common to all sorts of waves, it is not absolutely necessary to use sound waves for the home cinema model measurements. More profitable is the use of light as a substitute of sound. The detection of the energy distribution in the home cinema room can be carried out by photocells or by photography.
Although physical models of dedicated home cinemas have proven to be a very useful tool for the acoustical design, they are being superseded gradually by a cheaper, faster and more efficient method, namely by digital simulation of sound propagation in enclosures. The introduction of the digital computer into room acoustics is probably due to M.R. Schroeder and his co-workers digital cinema. Meanwhile, computer simulation has been applied not only to home cinema systems, but to factories, auditorium and other working spaces as well.
Basically, there are two methods of sound field simulation in use nowadays, for home cinema designs; namely ray tracing and the method of image sources, and both are based on geometrical acoustics. The most tedious and time consuming part of the whole process is the collection and input of room data such as the positions and orientations of the home cinema’s walls and their acoustic properties. One can study the combined effect of more than one source, and take into consideration all home cinema speakers together. This permits home cinema designers to determine the optimal configuration of a speaker installation in a home cinema system.
There are various computer based programs on the market today. They do not all guarantee the same accuracy, so it is up to the home cinema designer’s experience to decide which one computes better and reliable results. The computerised design of a home cinema room can be a big benefit; the software operator is able to alter things and achieve a smooth and pleasant result for the home cinema’s seating area. It is done prior to the home cinema installation and can achieve great acoustical end results.