Method for testing noise reduction coefficient of sound barrier material

Abstract

The invention discloses a method for testing the noise reduction coefficient of a sound barrier material. The method comprises the following steps: putting a plate-shaped test piece made of a noise reduction material into a reverberation chamber; sound absorption coefficients alpha s under different frequency bands are measured, a sound absorption coefficient curve graph is drawn, and the maximum sound absorption coefficient alpha max of the noise reduction material is determined; determining a minimum frequency fmin and a maximum frequency fmax corresponding to a half of the maximum sound absorption coefficient according to the sound absorption coefficient curve graph, and determining a frequency band delta f = [fmin, fmax] according to the fmin and the fmax; and according to the traffic noise frequency band delta fT, determining the traffic noise frequency band width Card (delta fT), determining the effective sound absorption frequency band delta f (delta fT) of the material, determining the effective sound absorption frequency band width Card (delta f (delta fT)), and further determining the noise reduction coefficient epsilon of the material in the traffic noise application. The method for testing the noise reduction coefficient of the sound barrier material has the advantages that the noise reduction performance of the sound barrier can be analyzed and evaluated through the noise reduction coefficient evaluation index, and the sound absorption characteristic and effect of the material can be accurately reflected.

Description

Technical Field

[0001] The invention relates to a method for testing the performance of noise reduction materials, in particular to a method for testing the noise reduction coefficient of a sound barrier material. Background Art

[0002] Noise reduction materials are materials that can reduce or eliminate the propagation of sound. They are widely used in many fields such as construction, transportation, and audio equipment to reduce the impact of noise on the environment and people. These materials achieve noise reduction effects through different mechanisms, including absorption, reflection, and blocking of sound.

[0003] Sound barriers are mainly used for sound insulation and noise reduction of roads, highways, elevated composite roads and other noise sources. In recent years, sound barriers have been widely used on roads and railways as an effective measure for traffic noise reduction. In the design of sound barriers, the sound absorption coefficient of the material is measured with reference to "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes Part 1: Standing Wave Ratio Method" (GB / T 18696.1-2004), "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes Part 2: Transfer Function Method" (GB / T 18696.2-2002) or "Sound Absorption Measurement in Reverberation Chambers" (GB / T 20247-2006) to confirm the noise reduction performance of the material. Among them, NRC (Noise Reduction Coefficient) is an important indicator for measuring the noise reduction performance of sound barriers, and is often used to quickly compare and screen sound barrier materials with strong acoustic performance.

[0004] With the changes in vehicle types, driving speeds, road conditions, etc., existing traffic noise has gradually shifted to medium and high frequencies. Traditional sound barriers can no longer perfectly match the current traffic noise characteristics, and the noise reduction effect is relatively poor. At the same time, the traditional evaluation index NRC only performs a weighted average of the sound absorption coefficients in the four frequency bands of 250Hz, 500Hz, 1000Hz, and 2000Hz, which cannot truly reflect the noise reduction effect of the screen material in actual traffic.

[0005] Therefore, the existing noise reduction performance index NRC of sound barriers is obtained through traditional noise reduction material analysis and measurement methods, which cannot accurately reflect the real performance of sound barriers in traffic noise control and cannot guide the design of sound barriers. Therefore, it is urgent to study a test method for the performance parameters of noise reduction materials suitable for modern traffic conditions to solve this technical problem. Summary of the invention

[0006] The present invention is to avoid the deficiencies existing in the above-mentioned prior art and provide a testing method for the noise reduction coefficient of sound barrier materials to determine the sound absorption coefficient of the sound barrier manufacturing material at different frequencies and accurately reflect the sound absorption characteristics of the material.

[0007] The present invention adopts the following technical solutions to solve the technical problems.

[0008] A method for testing the noise reduction coefficient of a sound barrier material of the present invention comprises the following steps:

[0009] Step 1: Make the noise reduction material used to make the sound barrier into a plate-shaped test piece;

[0010] Step 2: Use the reverberation chamber method to measure the sound absorption coefficient α of the noise reduction material in different frequency bands of 100Hz≤f≤5000Hz s , and draw a curve of sound absorption coefficient;

[0011] Step 3: According to the sound absorption coefficient α s And the sound absorption coefficient curve, determine the maximum sound absorption coefficient α of the noise reduction material max ;

[0012] Step 4: According to the sound absorption coefficient curve, determine half of the maximum sound absorption coefficient α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max ;

[0013] Step 5: According to the minimum frequency f min and the maximum frequency f max , determine the sound absorption coefficient as α max / 2 corresponds to the frequency band Δf = [f min ,f max ];

[0014] Step 6: Based on the traffic noise frequency band Δf T , determine the traffic noise bandwidth Card(Δf T );

[0015] Step 7: According to Δf and Δf T , calculate the effective sound absorption band of the noise reduction material Δf∩Δf T , determine the effective sound absorption bandwidth Card(Δf∩Δf T );

[0016] Step 8: Calculate the noise reduction coefficient ε of the noise reduction material in the traffic road.

[0017] The testing method of the noise reduction coefficient of a sound barrier material of the present invention is also characterized in that:

[0018] In specific implementation, in step 2, when no plate-shaped test piece is placed in the reverberation chamber, the calculation formula for the sound absorption amount A1 of the empty reverberation chamber is:

[0019]

[0020] In formula (1), V is the volume of the empty reverberation chamber, c1 is the propagation speed of sound in the air in the empty reverberation chamber; T1 is the reverberation time of the empty reverberation chamber; m1 is the sound intensity attenuation coefficient under the condition of the empty reverberation chamber;

[0021] After placing the plate-shaped test piece, the calculation formula for the sound absorption A2 of the reverberation chamber is:

[0022]

[0023] In formula (2), c2 is the propagation speed of sound in the air in the reverberation chamber after the plate-shaped test piece is placed; T2 is the reverberation time of the reverberation chamber after the plate-shaped test piece is placed; and m2 is the sound intensity attenuation coefficient under the reverberation chamber conditions after the plate-shaped test piece is placed.

[0024] In the specific implementation, in step 2, the sound absorption of the plate-shaped test piece A T The calculation formula is:

[0025]

[0026] The sound absorption coefficient α s The calculation formula is:

[0027]

[0028] In formula (4), S is the area of ​​the plate-shaped test piece.

[0029] In specific implementation, in step 4, if α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max If it is not in the interval [100, 5000], then take the minimum frequency f min =100Hz or maximum frequency f max =5000Hz.

[0030] In the specific implementation, in step 5, according to the traffic noise frequency band Δf T , traffic noise frequency band Δf T The bandwidth is Card(Δf T ).

[0031] In specific implementation, the calculation formula of the noise reduction coefficient ε is:

[0032]

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The present invention discloses a method for testing the noise reduction coefficient of a sound barrier material, comprising the following steps: making the noise reduction material into a plate-shaped test piece; placing the plate-shaped test piece in a reverberation chamber, and measuring the sound absorption coefficient α under different frequency bands. s And draw a sound absorption coefficient curve to determine the maximum sound absorption coefficient α of the noise reduction material max ; Determine the two sound absorption coefficients α that are half of the maximum sound absorption coefficient according to the sound absorption coefficient curve max / 2, according to the two α max / 2 determines the frequency band Δf corresponding to the 1 / 3 octave center frequency. If α max / 2 corresponds to a 1 / 3 octave center frequency that exceeds [100,5000] Hz. According to the actual test situation, the cutoff frequency is 100 Hz or 5000 Hz. According to the traffic noise frequency band Δf T And determine the traffic noise bandwidth Card(Δf T ), determine the effective sound absorption frequency band of the material Δf∩Δf T And determine the effective sound absorption bandwidth Card (Δf∩Δf T ), determine the noise reduction coefficient ε of the material in traffic noise applications.

[0035] The testing method of the noise reduction coefficient of the sound barrier material of the present invention has the advantages of being able to analyze and evaluate the noise reduction performance of the sound barrier through the noise reduction coefficient of the noise reduction material, and accurately reflecting the sound absorption characteristics and effects of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of a method for testing the noise reduction coefficient of a sound barrier material of the present invention.

[0037] Figure 2 It is a schematic diagram of measuring the sound absorption coefficient of a noise reduction material using the reverberation chamber method of the present invention.

[0038] Figure 3 This is a field test diagram of the sound absorption coefficient of the granular rock board in Example 1 of the present invention.

[0039] Figure 4 It is a sound absorption coefficient curve diagram of Example 1 of the present invention.

[0040] Figure 5 This is a field test diagram of the sound absorption coefficient of the double-coated metal plate in Example 2 of the present invention.

[0041] Figure 6 It is a sound absorption coefficient curve diagram of Example 2 of the present invention. DETAILED DESCRIPTION

[0042] See also Figure 1 to Figure 6 A method for testing the noise reduction coefficient of a sound barrier material of the present invention comprises the following steps:

[0043] Step 1: Make the noise reduction material used to make the sound barrier into a plate-shaped test piece;

[0044] Step 2: Use the reverberation chamber method to measure the sound absorption coefficient α of the noise reduction material in different frequency bands of 100Hz≤f≤5000Hz s , and draw a curve of sound absorption coefficient;

[0045] When 100Hz≤f≤5000Hz, the 1 / 3 octave center frequency f corresponding to f includes 100Hz, 125Hz, 160Hz, 200Hz, 250Hz, 315Hz, 400Hz, 500Hz, 630Hz, 800Hz, 1000Hz, 1250Hz, 1600Hz, 2000Hz, 2500Hz, 3150Hz, 4000Hz, and 5000Hz.

[0046] Step 3: According to the sound absorption coefficient α s And the sound absorption coefficient curve, determine the maximum sound absorption coefficient α of the noise reduction material max ;

[0047] Step 4: According to the sound absorption coefficient curve, determine half of the maximum sound absorption coefficient α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max ;

[0048] Step 5: According to the minimum frequency f min and the maximum frequency f max , determine the sound absorption coefficient as α max / 2 corresponds to the frequency band Δf = [f min ,f max ];

[0049] If α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max If it is not in the interval [100, 5000], then according to the actual test situation, the cutoff frequencies at both ends of the interval [100, 5000] are taken, that is, the two boundary values ​​of [100, 5000] are 100Hz or 5000Hz;

[0050] Step 6: Based on the traffic noise frequency band Δf T , determine the traffic noise bandwidth Card(Δf T );

[0051] In the present invention, the traffic noise frequency band Δf is taken as T =[250, 1000] Hz, the Card function represents the width of the noise frequency band, that is, the length of the interval [250, 1000]: 1000-250=750.

[0052] Step 7: According to Δf and Δf T , calculate the effective sound absorption band of the noise reduction material Δf∩Δf T , determine the effective sound absorption bandwidth Card(Δf∩Δf T );

[0053] Δf∩Δf T Represents the intersection operation of these two frequency bandwidths.

[0054] Step 8: Calculate the noise reduction coefficient ε of the noise reduction material in the traffic road.

[0055] like Figure 1 The present invention provides a method for testing the noise reduction coefficient of a sound barrier material. The method determines the sound absorption coefficient of the noise reduction material at different frequencies by using the reverberation chamber method for the main frequency range of traffic noise. Then the maximum sound absorption coefficient α is determined. max , draw a sound absorption curve, and determine the maximum sound absorption coefficient half α according to the sound absorption coefficient curve max / 2 corresponds to the minimum frequency f min and the maximum frequency f max , then according to the minimum frequency f min and the maximum frequency f max Determine the corresponding frequency band Δf, according to the traffic noise frequency band Δf T , determine the traffic noise bandwidth Card(Δf T ), according to Δf and Δf T , determine the effective sound absorption band of the material Δf∩Δf T , determine the effective sound absorption bandwidth Card(Δf∩Δf T ), analyze the sound absorption characteristics of the material, and obtain the noise reduction coefficient ε. The larger the noise reduction coefficient ε, the better the noise reduction effect of the material. Therefore, this method can determine the noise reduction effect of the sound barrier by the size of the noise reduction coefficient ε. The present invention combines the main frequency range of traffic noise and proposes a test method for the noise reduction coefficient of sound barrier materials, which has a positive effect on the preparation of materials, the verification of the noise reduction effect of sound barrier projects, and the reduction of noise along traffic lines.

[0056] In specific implementation, in step 2, when no plate-shaped test piece is placed in the reverberation chamber, the calculation formula for the sound absorption amount A1 of the empty reverberation chamber is:

[0057]

[0058] In formula (1), V is the volume of the empty reverberation chamber, c1 is the propagation speed of sound in the air in the empty reverberation chamber; T1 is the reverberation time of the empty reverberation chamber; m1 is the sound intensity attenuation coefficient under the condition of the empty reverberation chamber;

[0059] After placing the plate-shaped test piece, the calculation formula for the sound absorption A2 of the reverberation chamber is:

[0060]

[0061] In formula (2), c2 is the propagation speed of sound in the air in the reverberation chamber after the plate-shaped test piece is placed; T2 is the reverberation time of the reverberation chamber after the plate-shaped test piece is placed; and m2 is the sound intensity attenuation coefficient under the reverberation chamber conditions after the plate-shaped test piece is placed.

[0062] like Figure 3 and Figure 5 The schematic diagram of the reverberation chamber method test is shown in FIG. The sound intensity attenuation coefficient of the same reverberation chamber is a constant, and in Examples 1 and 2, m1=m2.

[0063] In the specific implementation, in step 2, the sound absorption of the plate-shaped test piece A T The calculation formula is:

[0064]

[0065] The sound absorption coefficient α s The calculation formula is:

[0066]

[0067] In formula (4), S is the area of ​​the plate-shaped test piece, that is, Figure 2 , Figure 3 and Figure 5 The area of ​​the upper surface of the plate-shaped test piece.

[0068] In specific implementation, in step 4, if α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max If it is not in the interval [100, 5000], then take the minimum frequency f min =100Hz or maximum frequency f max =5000Hz.

[0069] In the specific implementation, in step 5, according to the traffic noise frequency band Δf T , traffic noise frequency band Δf T The bandwidth is Card(Δf T ).

[0070] In specific implementation, the calculation formula of the noise reduction coefficient ε is:

[0071]

[0072] The present invention is further described below through two specific embodiments in conjunction with the accompanying drawings.

[0073] Example 1

[0074] like Figure 3 The particle rock board is taken as the research object. The area S of the particle rock board specimen is 11.76m 2 The volume V of the empty reverberation room is 237m 3 , the air temperature is 15℃, and the sound propagation speeds c1 and c2 in the air are both 340.45m / s under the conditions of empty field and reverberation chamber after placing the specimen. According to the test specification of "Sound Absorption Measurement of Reverberation Chamber" (GB / T 20247-2006), the reverberation time T1 of the empty reverberation chamber and the reverberation time T2 of the reverberation chamber after placing the specimen are measured, see Table 1 below.

[0075] Table 1 Reverberation time T1 and T2 of the empty field and the reverberation room with the test specimen of the granular rock plate material in Example 1

[0076] Frequency / Hz 100 125 160 200 250 315 400 500 630 <![CDATA[T1 / s]]> 10.37 10.18 9.53 9.35 8.10 7.66 6.11 4.84 3.80 <![CDATA[T2 / s]]> 10.53 10.64 11.21 11.34 10.49 10.85 8.83 8.17 6.80 Frequency / Hz 800 1000 1250 1600 2000 2500 3150 4000 5000 <![CDATA[T1 / s]]> 3.15 2.85 2.55 2.34 2.09 1.86 1.54 1.27 1.02 <![CDATA[T2 / s]]> 6.08 5.89 5.62 4.92 3.93 3.13 2.36 1.74 1.33

[0077] In Table 1, taking the 1 / 3 octave center frequency of 1000Hz as an example, according to formula (3), the sound absorption A of the plate-shaped test piece with a frequency of 1000Hz is calculated: T . Where, V = 237m 3 , c1=c2=340.45m / s, T1=2.85s, T2=5.89s; in this embodiment 1, m1=m2.

[0078]

[0079] Then, according to formula (4), the sound absorption coefficient αs at a frequency of 1000 Hz is calculated. S = 11.76 m 2 .

[0080]

[0081] Taking this as an example, calculate the sound absorption coefficient α at the 18 1 / 3 octave center frequencies in Table 1 above: s , the calculation results are shown in Table 2.

[0082] Table 2 Sound absorption coefficient α of granular rock board material of Example 1 at different 1 / 3 octave center frequencies s

[0083] Frequency / Hz 100 125 160 200 250 315 400 500 630 <![CDATA[Sound absorption coefficient α s > 0.00 0.01 0.05 0.06 0.09 0.13 0.16 0.28 0.38 Frequency / Hz 800 1000 1250 1600 2000 2500 3150 4000 5000 <![CDATA[Sound absorption coefficient α s > 0.50 0.59 0.70 0.73 0.74 0.71 0.74 0.70 0.76

[0084] The sound absorption coefficient curve of Example 1 is plotted according to the data in Table 2. Figure 4 shown.

[0085] It can be seen from Table 2 that the maximum sound absorption coefficient of the granular rock board is α max is 0.76, the maximum sound absorption coefficient α maxHalf of α max / 2 is 0.38. Figure 4 , the left end of the noise frequency corresponding to 0.38 is 630Hz, that is, the minimum frequency f min =630Hz; the other end on the right side exceeds the cut-off frequency 5000Hz, so the maximum frequency f is taken max =5000Hz. Then α max / 2=0.38 corresponds to a frequency band of Δf=[630,5000] Hz. In Example 1, the frequency band of traffic noise Δf T = [250, 1000] Hz, calculate the traffic noise bandwidth Card (Δf T )as follows.

[0086] Card(Δf T )=1000-250=750

[0087] The effective sound absorption frequency band of the granular rock board is Δf∩Δf T =[630,1000]∩[250,1000]=[630,1000]Hz, calculate the effective sound absorption bandwidth Card(Δf∩Δf T )as follows.

[0088] Card(Δf∩Δf T )=1000-630=270

[0089] Then, according to formula (5), the noise reduction coefficient ε=0.27 is calculated. The specific calculation process is as follows.

[0090]

[0091] Example 2

[0092] like Figure 5 The double-coated metal plate is taken as the research object. The area S of the double-coated metal plate specimen is 11.76m 2 The volume V of the empty reverberation room is 237m 3 , the air temperature is 18℃, and the sound propagation speeds c1 and c2 in the air are both 342.45m / s under the conditions of empty field and reverberation chamber after placing the specimen. According to the test specification of "Sound Absorption Measurement of Reverberation Chamber" (GB / T 20247-2006), the reverberation time T1 of the empty reverberation chamber and the reverberation time T2 of the reverberation chamber after placing the specimen are measured, see Table 3.

[0093] Table 3 Reverberation time T1 and T2 of the reverberation room with empty space and test piece of the double-coated metal plate material in Example 2

[0094] Frequency / Hz 100 125 160 200 250 315 400 500 630 <![CDATA[T1 / s]]> 3.76 3.94 3.21 2.71 2.48 2.61 2.39 2.39 2.47 <![CDATA[T2 / s]]> 11.29 11.28 11.02 11.12 10.42 10.77 8.73 8.12 7.03 Frequency / Hz 800 1000 1250 1600 2000 2500 3150 4000 5000 <![CDATA[T1 / s]]> 2.35 2.44 2.49 2.47 2.42 2.27 2.09 1.79 1.50 <![CDATA[T2 / s]]> 6.58 6.70 6.95 6.59 5.78 4.90 3.86 2.96 2.19

[0095] Similar to Example 1, in Table 3, taking the 1 / 3 octave center frequency of 1000 Hz as an example, according to formula (3), the sound absorption A of the plate-shaped test piece at a frequency of 1000 Hz is calculated: T . Where, V = 237m 3 , c1=c2=342.25m / s, T1=2.44s, T2=6.70s; m1=m2.

[0096]

[0097] Then, according to formula (4), the sound absorption coefficient α at a frequency of 1000 Hz is calculated: s . S=11.76m 2 .

[0098]

[0099] Taking this as an example, calculate the sound absorption coefficient α at the 18 1 / 3 octave center frequencies in Table 3 above: s , the calculation results are shown in Table 4.

[0100] Table 4 Sound absorption coefficient α of double-coated metal plate material in Example 2 at different 1 / 3 octave center frequencies s

[0101] Frequency / Hz 100 125 160 200 250 315 400 500 630 <![CDATA[Absorption coefficient α s > 0.58 0.54 0.72 0.91 1.00 0.94 0.99 0.96 0.86 Frequency / Hz 800 1000 1250 1600 2000 2500 3150 4000 5000 <![CDATA[Sound absorption coefficient α s > 0.89 0.85 0.84 0.82 0.78 0.77 0.72 0.71 0.69

[0102] The sound absorption coefficient curve of Example 2 is plotted according to the data in Table 4. Figure 6 shown.

[0103] It can be seen from Table 4 that the maximum sound absorption coefficient α of the double-coated metal plate max is 1.00, the maximum sound absorption coefficient α max Half of 0.5. Figure 6 , the frequencies on the left and right sides corresponding to 0.5 are both higher than the cutoff frequencies at both ends. Therefore, the minimum frequency f min =100Hz; the other end on the right side exceeds the cut-off frequency 5000Hz, so the maximum frequency f is taken max =5000Hz.

[0104] Therefore, Δf = [100, 5000] Hz. The traffic noise frequency band Δf in Example 2 T = [250, 1000] Hz, calculate the traffic noise bandwidth Card (Δf T )as follows.

[0105] Card(Δf T )=1000-250=750

[0106] The effective sound absorption band of the double-coated metal plate is Δf∩Δf T = [100, 5000] ∩ [250, 1000] = [250, 1000] Hz, calculate the effective sound absorption bandwidth Card (Δf ∩ Δf T )as follows.

[0107] Card(Δf∩Δf T )=1000-250=750

[0108] Then, according to formula (5), the noise reduction coefficient ε=1 is calculated. The specific calculation process is as follows.

[0109]

[0110] The noise reduction coefficient of the particle rock board ε = 0.27 and the noise reduction coefficient of the double-coated metal board ε = 1 show that the noise reduction effect of the double-coated metal board is much greater than that of the particle rock board. In this way, the staff can have an intuitive and accurate understanding of the noise reduction performance of the two materials.

[0111] The testing method of the noise reduction coefficient of the sound barrier material of the present invention finally determines the noise reduction effect of the noise reduction material in traffic after being made into a sound barrier based on the calculated noise reduction coefficient ε, thereby being able to quantitatively describe and analyze the noise reduction effect of the sound barrier.

[0112] The testing method for the noise reduction coefficient of the sound barrier material of the present invention determines the sound absorption coefficient of the material at different frequencies through the reverberation chamber method, analyzes the sound absorption characteristics of the material according to the maximum sound absorption coefficient and the effective sound absorption frequency band, and combines the main frequency range of traffic noise, which has a positive effect on the preparation of materials, the verification of the noise reduction effect of sound barrier projects, and the reduction of noise along traffic lines.

[0113] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0114] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for testing the noise reduction coefficient of a sound barrier material, characterized in that: The steps include: Step 1: Make the noise reduction material used to make the sound barrier into a plate-shaped test piece; Step 2: Use the reverberation chamber method to measure the sound absorption coefficient α of the noise reduction material in different frequency bands of 100Hz≤f≤5000Hz s , and draw a curve of sound absorption coefficient; Step 3: According to the sound absorption coefficient α s And the sound absorption coefficient curve, determine the maximum sound absorption coefficient α of the noise reduction material max ; Step 4: According to the sound absorption coefficient curve, determine half of the maximum sound absorption coefficient α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max ; Step 5: According to the minimum frequency f min and the maximum frequency f max , determine the sound absorption coefficient as α max / 2 corresponds to the frequency band Δf = [f min ,f max ]; Step 6: Based on the traffic noise frequency band Δf T , determine the traffic noise bandwidth Card(Δf T ); Step 7: According to Δf and Δf T , calculate the effective sound absorption band of the noise reduction material Δf∩Δf T , determine the effective sound absorption bandwidth Card(Δf∩Δf T ); Step 8: Calculate the noise reduction coefficient ε of the noise reduction material in the traffic road.

2. A method for testing the noise reduction coefficient of a sound barrier material according to claim 1, characterized in that: In step 2, when no plate-shaped test piece is placed in the reverberation chamber, the calculation formula for the sound absorption amount A1 of the empty reverberation chamber is: In formula (1), V is the volume of the empty reverberation chamber, c1 is the propagation speed of sound in the air in the empty reverberation chamber; T1 is the reverberation time of the empty reverberation chamber; m1 is the sound intensity attenuation coefficient under the condition of an empty reverberation chamber; After placing the plate-shaped test piece, the calculation formula for the sound absorption A2 of the reverberation chamber is: In formula (2), c2 is the propagation speed of sound in the air in the reverberation chamber after the plate-shaped test piece is placed; T2 is the reverberation time of the reverberation chamber after the plate-shaped test piece is placed; and m2 is the sound intensity attenuation coefficient under the reverberation chamber conditions after the plate-shaped test piece is placed.

3. The method for testing the noise reduction coefficient of a sound barrier material according to claim 2, characterized in that: In step 2, the sound absorption A of the plate-shaped test piece T The calculation formula is: The sound absorption coefficient α s The calculation formula is: In formula (4), S is the area of ​​the plate-shaped test piece.

4. The method for testing the noise reduction coefficient of a sound barrier material according to claim 1, characterized in that: In step 4, if α max / 2 corresponds to the minimum frequency f min and the maximum frequency f max If it is not in the interval [100, 5000], then take the minimum frequency f min =100Hz or maximum frequency f max =5000Hz.

5. The method for testing the noise reduction coefficient of a sound barrier material according to claim 1, characterized in that: In step 5, according to the traffic noise frequency band Δf T , traffic noise frequency band Δf T The bandwidth is Card(Δf T ).

6. The method for testing the noise reduction coefficient of a sound barrier material according to claim 1, characterized in that: The calculation formula of the noise reduction coefficient ε is:

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