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Modeling is a nice tool, both for the specialist and for public information. Like all tools, it does have limitations and cannot be trusted blindly! While it is nice to establish a comparison between different situations—provided the model has been properly elaborated—it seldom comes up with an absolute value to be trusted and cannot be operated by nonspecialists. Here the problem is especially complicated by the numerous volumes (stage, hall, orchestra pit), as well as by the somewhat elaborate decorations used for the inner surfaces of the facility.

Ray Tracing Modeling

Ray tracing using a computer does look the part. However, the physically minded can quickly understand that solving the wave equation inside a hall full of singularities, such as balconies, coupled volumes (e.g., orchestra pit, back stage), and funny-looking surfaces (including curved surfaces and complex decorated walls), is not going to be easy, not to say accurate. Nevertheless, ray tracing is rather quick to implement (especially if the architect has previously been talked into providing the relevant drawings suitably clean of unnecessary details) and can be used to pinpoint and correct such defects as echoes and inadequate reverberation time.

Some commercial programs now provide auralization modules that enable the user to hear how the hall under study will eventually sound. This may come in handy when it comes to the discussion of the balance between the orchestra and singers.

Scale Modeling

Scale modeling may look old fashioned, but it always features a kind of magic to onlookers. Actually, one may discuss scattering objects for hours in front of a dubious client using some computer simulation results and images without much success, but having the client look at a scale model while being told the problem is usually quite effective, not to say awesome.

Scale modeling proves efficient when dealing with singularities such as balconies, coupled volumes, and funny-looking surfaces.

What scale should be used? Clearly enough, the smaller the scale, the higher the frequency range will be and the more complicated the measurements will turn out, as air absorption becomes quite a problem. Scales like 1/10 to 1/16 are rather nice and popular, as air absorption is not yet too much of a problem, but while the model is easy to work with, it also happens to be quite cumbersome. Experiments have been performed with cardboard 1/50 models [4].

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