Sound Transmission through Hollow Brick Walls

Abstract

Hollow bricks and blocks are one of the most common forms of material used for wall construction found in Central and Southern Europe. The principle purpose of the perforations (holes) is to increase the thermal insulation properties. As a result of these perforations the block gross density is reduced significantly and these block walls have high anisotropy. Consequently, the acoustical insulation properties are influenced detrimentally in comparison to solid blocks. Due to the large thickness of some of these types of hollow block thick wall effects can occur such as bending shear waves and thickness resonances. These further reduce the sound insulation at high frequencies. This paper describes the characteristic features of sound transmission through hollow walls. For this study several different types of wall were built of varying thickness and materials and the sound reduction index was recorded. The effects of additional plaster layers is also discussed. It is suggested that the material properties of the block's complex web structure may strongly influence the sound reduction index at the low and high frequencies.

Prediction of the sound reduction index of clay hollow brick walls

“…As discussed by Fringuellino and Smith, 6 the trend in the high-frequency range (above 2000 Hz) is due to two different types of mechanisms related to the thickness of the walls: shear waves and thickness resonance. Different from thin walls, where the bending wave speed increases with frequency, for thick walls the shear deformation and the rotational inertia limit the group and phase wave speeds to a common value at high frequencies.…”

“…These aspects may strongly influence the sound reduction index of the wall, as shown by Fringuellino and Smith. 6 In this respect, empirical derivations are a possible way to estimate the performances of commercially available materials. For example, Di Bella et al 7,8 used experimental measurements to identify the empirical spectrum of sound insulation performances of cross-laminated timber elements and to propose generalised reference curves.…”

Comparative study of fire resistance and acoustic performance of ceramic brick walls in concern to NBR 15575 in residential buildings in Brazil

“…It is possible to verify that both samples had an accentuate sound reduction index in 100 Hz provided by their stiffness, decreasing and differing in the others low frequency bands, characteristic of the coincidence valley commented by Fringuellino and Smith (1999), in the first resonance controlled zone, varying as a function of the damping mechanisms of each brick composition. The two samples resemble each other again in the mid frequency bands, in the mass controlled zone, differing only in the 400 to 630 Hz bands.…”

Análise Do Isolamento Sonoro a Sons Aéreos De Alvenarias Com Blocos Cerâmicos Vazados Utilizando Revestimento Em Argamassa Cimentícia

“…Nos sistemas de vedações verticais compostos por alvenaria de blocos cerâmicos, os elementos vazados tornam a transmissão sonora complexa, com forte dependência da geometria dos furos e espessura total do sistema, tendo como consequência a redução de massa superficial. Além disso, os vazados aumentam a ressonância interna nos blocos, com uma considerável redução na capacidade de isolamento acústico [10].…”