Acoustic treatment and soundproofing of buildings

Following on from room acoustics which provides a geometrical, wave-like and statistical approach to the laws governing the behavior of sound waves in enclosed spaces, this article presents the physical principles underlying absorption and transmission phenomena, as well as the concrete approaches that can be derived from them in the acoustic treatment of walls.

Rather than presenting the absorption characteristics of different types of coating in a conventional way, we have chosen to develop a very general physical model, applicable to all materials.

In the first part, the proposed model comprises a rigid and a compliant part. It can therefore account for the behavior of absorbers whose dissipative contribution due to structural deformations (textile fibers, porous foams, felts, etc.) can be neglected. This paragraph is completed by a method for "shaping" the room response curve by applying the proposed principles.

The second part takes up in greater detail the concepts discussed above, and successively examines the calculation of diaphragms, resonators, perforated plates and weakly deformable porous structures, as well as most combinations of these different elements. In each case, a number of concrete examples are given.

The third part summarizes the main physical laws involved in the transmission of sound waves through walls. It emphasizes the importance of bending waves and their impact on coincidence phenomena. It enables us to assess the main critical values that constitute the weak points of partitions, doors, glazing, etc.

The impact of these laws on the efficiency of double walls is illustrated by a few typical examples.