# Possibilities of Evaluating the Effectiveness of Noise Barriers in Slovakia
## 3 Results
### Measurement of Sound Insulation of the Noise Barrier 275-D4 JS In Situ Using the Adrienne Method  
The measurement of the barrier by the Adrienne method was performed on the D4 motorway at km 16.826. The location selection was such that no other sound-reflecting and sound-bending objects were present.  
The tested noise barrier was a single-layer barrier built of three types of panels:  
* 0.8-m-high concrete plinth;
* Panel SGRABS500-V: 1.2-0.8 from the manufacturer Sugremin, C/Cronos 10, 4a planta, local 1 28,037 Madrid Spain--installed from 0.8 m to a height of 2.3 m of the total height of the noise barrier; and
* Polycarbonate panel installed from a height of 2.3 m of the total height of the noise barrier. The height of the installed polycarbonate panel varied along the length of the noise barrier. The noise barrier panels were placed on steel I-profiles spaced 3 m and 4 m apart. The overall dimensions of the test specimen were 4.8 m \(\times\) 7.0 m (height \(\times\) width). The total thickness of the panel was 0.1 m.  
Figure 12 shows the location of the noise source (a) and the set of nine microphones (b).  
\(D_{M}=0.25\) m--horizontal distance (microphone grid, microphone no. 5--reference plane of the source) at a height \(h_{S}\);  
\(d_{S}=1.0\) m--horizontal distance (loudspeaker--reference plane of the source) at a height \(h_{S}\);  
\(h_{B}=4.8\) m--height of the barrier;  
\(h_{S}=2.4\) m--reference height of the loudspeaker;  
\(t_{B}=0.1\) m--thickness of the barrier at height \(h_{S}\).  
Figure 12: (a) Location of the sound source; (b) location of the microphone set in situ.  
The measurement was done according to the norm EN 1793-6 [29]. The duration of Adrienne temporal window was 7.9 ms and the low-frequency limit was 166 Hz. The noise source was a regulated artificial sound source.  
The used measurement instrumentation included:  
* Analyser Apollo_lt_2B--Analyzer for Sound and Vibration;
* Microphone M400. B;
* Amplifier ATLAS PA601 Power Amplifier--Single Channel, 60-Watt Power Amplifier with Global Power Supply; and
* AcoustiA Adrienne Base Module.  
The wiring and measurement diagram according to the Adrienne system is shown in Figure 13.  
Measurement results:  
The single-number rating of sound insulation in the range of 200 to 5000 Hz of a polycarbonate panel (Figure 14) was calculated using:  
\[DL_{S,LE}=35\;\mathrm{dB} \tag{10}\]  
Measurement results:  
The single-number rating of sound insulation in the range of 200 to 500  
The single-number rating of sound insulation in the range of 200 to 5000 Hz of a pole (Figure 15) was calculated using:  
\[DL_{S,LP}=26\;\mathrm{dB} \tag{11}\]  
The overall single-number rating of the sound insulation of the barrierwas calculated according to Equation (9) (Figure 16):  
\[DL_{S,LG}=28\;\mathrm{dB} \tag{12}\]  
Measurement uncertainty:  
Reproducibility standard deviation for acoustic elements: 1.31 dB.  
Reproducibility standard deviation for poles: 0.92 dB.  
The airborne sound insulation index of the barrier determined by the Adrienne method could not be compared with the theoretical insertion loss of the noise barrier calculated according to the CNOSSOS method, because the sound insulation index and insertion loss are not the same quantities.  
Figure 16: Diagram from the measurement of the airborne sound insulation index of the barrier.  
Figure 15: Diagram from the measurement of the airborne sound insulation index of a pole.