Vibrometry Assessment of the External Thermal Composite Insulation Systems Influence on the Façade Airborne Sound Insulation †

Abstract

This paper verifies the impact of the use of an external thermal composite system (ETICS) on airborne sound insulation. For optimum accuracy over a wide frequency range, classical microphone based transmission measurements are combined with accelerometer based vibrometry measurements. Consistency is found between structural resonance frequencies and bending wave velocity dispersion curves determined by vibrometry on the one hand and spectral features of the sound reduction index, the ETICS mass-spring-mass resonance induced dip in the acoustic insulation spectrum, and the coincidence induced dip on the other hand. Scanning vibrometry proves to be an effective tool for structural assessment in the design phase of ETICS systems. The measured spectra are obtained with high resolution in wide frequency range, and yield sound insulation values are not affected by the room acoustic features of the laboratory transmission rooms. The complementarity between the microphone and accelerometer based results allows assessing the effect of ETICS on the sound insulation spectrum in an extended frequency range from 20 Hz to 10 kHz. The modified engineering ∆R prediction model for frequency range up to coincidence frequency of external plaster layer is recommended. Values for the sound reduction index obtained by a modified prediction method are consistent with the measured data.

On the use of dynamic vibration absorbers to counteract the loss of sound insulation due to mass-spring-mass resonance effects in external thermal insulation composite systems

“…In earlier publications, the present authors addressed the deterioration of the sound reduction index R at the mass-spring-mass resonance of the ETICS system using numerical models [4,5]. Experimental evidence of the occurrence of the dip in the sound reduction index was given in [6]. The present work addresses the use of an array of dynamic vibration absorbers, sometimes also referred to as a locally resonant metamaterial structure, to counteract ETICS resonance induced dip in the noise reduction index.…”

Characterizing the Frequency Response of Compliant Materials by Laser Döppler Vibrometry Coupled Acoustic Excitation

“…Roozen et al [20] used an array of loudspeakers to generate a diffuse field in building elements, measuring the response by laser vibrometry. Urban et al [21] proposed an approach to determine façade sound insulation by using an acoustic source, measure acoustic insulation by microphones, and analyze vibrometry in the tested structures using accelerometers.…”

Numerical Modelling of Thermal Insulation of Reinforced Concrete Ceilings with Complex Cross-Sections

“…As in the case of nondestructive testing, they will allow testing of thermal insulation of only small elements [17][18][19][20]. For ceilings with complex geometries, both nondestructive testing in small areas and laboratory testing of small samples do not give good results [21][22][23]. Correct results are obtained only when conducting thermal insulation tests on a natural scale, which, however, requires the construction of a full-size model, with walls, ceilings and window and door woodwork [21,22].…”

“…Correct results are obtained only when conducting thermal insulation tests on a natural scale, which, however, requires the construction of a full-size model, with walls, ceilings and window and door woodwork [21,22]. A good alternative here is to perform calculations using simple or complex calculation methods [21,23,24]. Recently, programs based on the finite element method (FEM) have been used more and more often to determine the penetration coefficient [25][26][27].…”