Drasko Masovic

Calculation of sound insulation according to EN 12354: Influence of type of the separating element junctions

Separating element junctions make a dual contribution in the calculations of sound insulation according to EN 12354 standards. Junction types and vibration reduction index values determine the amount of the vibration energy which will be transmitted from the separating to the flanking elements, and therefore the flanking transmission between the source and the receiving room. On the other hand, vibration reduction index values influence the structural reverberation time of the element, by quantifying energy losses at its junctions. The aim of this work is to quantify the influence of the separating element junction types on the calculated value of airborne and impact sound insulation.

Calculation of sound insulation according to EN 12354: Influence of sound reduction index of flanking elements

EN 12354 standards describe models for calculation of sound insulation in buildings. EN 12354-1 defines a model for airborne sound insulation, while EN 12354-2 describes the calculation procedure for impact sound insulation. Although the calculated value of sound insulation in both cases depends mostly on the insulation properties of the separating element, flanking transmission is also treated. The aim of this work is to assess the influence of sound reduction index of flanking elements (walls, floors and ceilings) on the calculated value of airborne and impact sound insulation.

Experimental verification of near-field beamforming using low-cost microphone array

Beamforming or spatial filtering is a technique used for achieving high directivity radiation patterns of sensor arrays. In recent decades it found its acoustic application through the development of acoustic camera and holography. This paper demonstrates the example of near-field beamforming. Eight low-cost microphones array was built and used for signal acquisition and spatial filtering is done by dedicated software. Despite the modest price of hardware components obtained results are solid and accurate.

Towards the improved prediction of airborne sound insulation in buildings

The focus of this paper is improving predictions of airborne sound insulation in buildings based on the classical model of sound transmission. Firstly, it is demonstrated that acoustic properties of real noise in buildings can have a critical influence on the rating values of sound insulation and their correlation with subjective impression of the achieved acoustic comfort. Secondly, the contributions of the most important descriptors of building elements and junctions between them are analysed. Finally, the two standardized models, detailed and simplified, are compared in various practical sound insulation scenarios.

Comparison of New measurement methods in building acoustics at low frequencies

New methods for obtaining impulse response of a room (ISO 18233) can be used in building acoustics for measurements of sound pressure level and reverberation time. In principle, application of MLS and swept-sine deterministic signals should help enhancing the effective signal-to-noise ratio and, therefore, the accuracy of measurements, compared to the classical interrupted noise method. The aim of this paper is to make the comparison between the two methods when implemented for low frequency measurements.

Low frequency measurements in building acoustics — Analysis of reverberation time field Measurement results

Many European countries consider changing current sound insulation regulative to make field measurements of sound insulation mandatory down to 50 Hz. This is also supported by newly proposed standards - ISO/CD 16283-1 (field measurements of sound insulation) and ISO/NWIP 16717-1 (deriving the single-number values). On the other hand there is a lack of data in literature about the measurement results and the uncertainty at such low frequencies. This paper analyzes about 300 results of field reverberation time measurements in the extended frequency range. The measurements are done by five independent institutions involved in EU COST Action TU0901 and gathered in a unique database as a part of STSM (Short Term Scientific Mission). Main objective of the Action is to propose sound insulation descriptors to be widely adopted by European countries.

Analysis of sound level in the orchestra pit of the National Theatre in Belgrade

As most musical instruments have the potential to produce high sound pressure levels, studies aimed at analyzing the sound level in rooms that are used for performances and rehearsals have become numerous. Orchestra pits represent a special case, where in a small and roofed over area a larger group of musicians, that is the sound source, is situated. This paper presents the results of the analysis of the sound level in the orchestra pit of the National Theatre in Belgrade.

A functional model of planar microphone array realized with low-cost microphones

This paper describes a realization of microphone array designed on initial assumption to incorporate low-cost multimedia microphones and standard laboratory equipment. Mechanical construction of the array is made of components find on market and some second-hand mechanical parts found in laboratory. Special preamplifiers were realized to work with wide range of low-cost microphones. Paper also presents subsystem designed for amplitude and phase aligns of the low-cost microphones in the array.