Methodological guide for the acoustic study of rooms. Linearized approach

Unlike the other fields of acoustics (vibratory behavior of sources, radiation, propagation, electroacoustics, etc.), which can be correctly approached on the basis of fundamental physical laws and their mathematical expression, room acoustics cannot, in any way, be the subject of a model describing mathematically the behavior of sound in a room (cf. introduction to the article [C 3360 ]). To make up for this deficiency, the various researchers who have been interested in this question since Antiquity have proposed a multitude of "little formulas" of various origins designed to evaluate the relative importance of one or more variables at a given point in the room and for a well-defined configuration. As a result, we now have a set of relationships based on considerations that are sometimes geometric, sometimes statistical, sometimes wave-like, but most often empirical or psychophysical.

These relationships can predict the value of a variable by various methods, but they rarely agree on the result and, in any case, when they do for a given configuration, they no longer do so as soon as the reference situation is deviated from even slightly (displacement of the measurement point, frequency band, variation in the number of listeners, temperature, etc.).

As a result, managing the multitude of specific relationships in room acoustics is a delicate operation which requires, in addition to knowledge of these different laws, a particular ability to select the most relevant ones and correctly make the transitions that separate or oppose them. While this difficulty can easily be circumvented in the case of small rooms, the same cannot be said for complex rooms, which require a much more consistent global vision. In the articles [BR1010] and [BE 1012] , we looked at two aspects of a coherent approach to optimizing certain parameters of complex room acoustics....