SUMMARY

Noise transmitted by the sidewalls of buildings represents a major acoustic insulation problem and calls for the adoption of new construction solutions opening up a whole range of possibilities. The current thesis addresses this issue.
First, a major review of the techniques and measuring models was realized, along with a prediction of the acoustic behaviour of materials that are potential candidates for use in constructions. As part of this, we particularly focused on the following two items: Materials to be used as acoustic absorbents, as well as materials to be used as flexible sheets in floating floors. Various types of materials were studied, particularly recycled or natural fibre materials, in order to determine their characteristics, which is needed in order to assess whether they are acoustic absorbents, and in addition, separate models for new materials were obtained. Different recycle materials and sheets were studied for evaluation of their efficiency in floating floors. This, then, is a presentation of a study of new construction materials providing an increased variety or facilitating the reuse and recycling of other products or waste. Moreover, the test uncertainty was studied in each case.
Another important element of the thesis consisted in applying and validating an “in situ” measurement method for lateral transmissions. No standard techniques are currently available, and standard tests exist in laboratories only for some construction solutions. Hundreds of different joint configurations were measured, combining rigid and flexible joints, and assessing the effect of floating floors, as well. The uncertainty of this type of tests was also studied, as were the conditions under which the results of the test are valid. All the acquired information yielded formulas that were adjusted, and various conclusions concerning certain joints could be drawn.
Finally, several other tools were included. Numerical tools are available for validating whether the finite-element method enables simulation of the state of joints, and the information needed for lateral transmission is thus provided. Scale models for studying the effect of lateral transmissions in order to do real-life comparisons and obtain parameters for their modelling in a controlled fashion also exist. All of this information was used to calculate the maximum possible acoustic isolation in a transmission chamber as a function of the sidewall to be tested.
Thus, the thesis provides a contribution to the development and validation of new absorbent materials and new flexible construction sheets, including devising measurement techniques and the prediction of losses occurring in sidewalls.