Advancements in Sound Reflection and Airborne Sound Insulation Measurement on Noise Barriers

Abstract

<span>The <i>in-situ</i> measurement of sound reflection and airborne sound insulation characteristics of a noise barrier in Europe are currently performed following the CEN/TS 1793-5 European standard guidelines (last revision published in 2003 [</span><span>1</span><span>]). After some years a large number of barriers measured, the original method has been significantly enhanced and validated in the frame of the EU funded QUIESST project, WP3 [</span><span>2</span><span>]. The sound reflection measurement method has been improved using a square 9-microphone grid not rigidly connected to the loudspeaker, an optimized alignment al</span><span>gorithm of free-field and reflected impulse responses, including fractional step shifts and least squares estimation of the best relative position, and a correction for geometrical divergence and sound source directivity. Each single measure</span><span>ment is then validated by means of the Reduction Factor calculation. The airborne sound insulation measurement method has not been markedly changed since 2003, because the procedure is robust and easily applicable as it is, but some problems may still be encountered when measuring highly insulating noise barriers, due to a poor signal to noise ratio of the transmitted impulse response. In those cases it is difficult to realize just after the measurement whether the obtained data are valid or not. A method, applicable on site, to overcome this problem is described here. It is based on the Signal to Noise Ratio estimation of critical parts of the acquired impulse responses and gives a strong validation criterion.</span><span></span> <p> <b><span></span></b> </p

Repeatability and Reproducibility of <I>In Situ</I> Measurements of Sound Reflection and Airborne Sound Insulation Index of Noise Barriers

“…This method has been validated by several authors, butthe repeatability and reproducibility of the method has been only occasionally estimated and reported in the literature [6,7,8,9]. The in situ method has been substantially improvedd uring the EU funded QUIESST project [10,11,12,13]. Moreover, in the same framework, an inter-laboratory test (ILT )has been carried out in order to assess the repeatability and reproducibility of the newly developed method when applied to real-life samples [13,14,15].…”

“…The in situ method has been substantially improvedd uring the EU funded QUIESST project [10,11,12,13]. Moreover, in the same framework, an inter-laboratory test (ILT )has been carried out in order to assess the repeatability and reproducibility of the newly developed method when applied to real-life samples [13,14,15].…”

A Comprehensive Review on the Effectiveness of Existing Noise Barriers commonly used in the Railway Industry

“…According to P. Guidorzi and M. Garai [26], several methods can be used to determine the effectiveness of noise barriers. The Adrienne method is one of the methods that can be used to measure in-situ sound reflection, diffraction and airborne sound insulation.…”

“…However, the height of a noise barrier does not necessarily have to be too high but it can be as high as 3m or 4 m [20] [23]. Nevertheless, noise barriers which are too long and too high cause other problems such as loss of sunlight and visual impact [26]. Therefore, the low height of noise barriers is mostly suitable for trains as the noise produced mainly originates from the rail tracks and bogie areas, which are close to the ground.…”

Acoustic evaluation of modular greenery noise barriers

“…The results are computed in one-third-octave frequency bands and describe the extent to which the device under test reflects a sound wave back towards its source. Recently, in the framework of the European QUIESST project, this method was thoroughly revised (Guidorzi and Garai, 2013;Garai et al, 2014). The method requires a minimum barrier width and height of 4 m to avoid the effect of ground reflections (if vertical rotation is chosen) or post reflections (if horizontal rotation is chosen).…”