The purpose of sound absorbing and insulating products is to limit the propagation of noise inside the premises in which noise is generated in the case of sound absorbing materials, and to the outside in the case of sound insulating materials. Thermal walls constitute both thermal insulation and noise absorbing materials. They improve the performances of composite sound insulating complexes. In certain conditions of application they may alone constitute sound insulation. They help to improve acoustic comfort by reducing the transmission and reverberation of airborne noise.
Acoustic insulation in the form of ISOTHERM projected onto a wire mesh:
The sound insulation of a concrete wall is generally improved by adding an insulating material (for instance mineral wool) protected by a waterproof facing. This forms a mass-spring-mass system which has a natural resonance frequency at which we observe reduced performance relative to the substrate but above which there is an increase in this performance. If this natural frequency is incorrectly situated in the interval of useful frequencies, the overall performances of the wall equipped with the reinforcing complex may decrease relative to that of the bare wall. Mineral wool that is sprayed directly onto the concrete also has a resonance frequency which can have an unfavourable effect. If the mineral wool is sprayed onto wire mesh fixed to the concrete and separated by a sheet of kraft paper, the resonance frequency is "poorly communicated" to the substrate and there is little loss of insulation at this frequency. We then observe an improvement in the performances of the support at higher frequencies.
Sound absorption using ISOTHERM or ISOFLAM SM:
Sound absorption contributes to correcting the sound levels in the room in which the source of the noise is located. It reduces the level of reverberation of the sounds in this room, for example a compressor room or a discotheque.
The absorption performance of a product is expressed in the form of an absorption coefficient alpha Sabine (αs) which is a function of the frequency su of the noise or a weighted coefficient αw. The closer the value to 1, the better the absorption.
The absorption coefficient of our products ISOTHERM and ISOFLAM SM in the 100 to 5000 Hz frequency range is from 0.08 in the low frequencies to 1 in the medium to high frequencies. This corresponds to a weighted coefficient w greater than or equal to 0.70 in accordance with standard NF EN ISO 354 supplemented by standard NF EN ISO 11654.
Even though at some frequencies laboratories give results that are slightly above 1 (essentially due to the relevance of the Sabine formula and possibly the edge effects of the tested sample), it is recommended that these results be limited to 1 since they cannot absorb more than they receive.