由图4.5可知，在125Hz~500Hz的中低频频段，不同类型路面的检

由图4.5可知，在125Hz~500Hz的中低频频段，不同类型路面的检修道噪声水平无明显差异；在125Hz以下的低频频段，长隧道内排水降噪路面路段的检修道噪声水平小于密级配路面路段；在500Hz以上的中高频频段，长隧道内排水降噪路面路段的检修道噪声水平密级配路面路段。由于排水降噪路面中大孔隙结构的吸声作用，所以降噪效果更优。<br>由图4.5可知，与车内噪声不同，检修道噪声的频谱分布显示大空隙路面有效降低了交通噪声的中低频噪声，因此车内噪声中的低频噪声可能来自于车身振动。

From Figure 4.5, it can be seen that there is no significant difference in the noise level of maintenance tracks on different types of road surfaces in the mid to low frequency range of 125Hz to 500Hz; In the low-frequency frequency band below 125Hz, the noise level of the maintenance track in the long tunnel drainage noise reduction road section is lower than that in the dense graded road section; In the medium to high frequency frequency band above 500Hz, the noise level of the maintenance track in the long tunnel drainage noise reduction road section is closely graded with the road section. Due to the sound absorption effect of the large pore structure in the drainage noise reduction road surface, the noise reduction effect is better.<br>From Figure 4.5, it can be seen that, unlike the noise inside the vehicle, the spectrum distribution of maintenance lane noise shows that the large gap road surface effectively reduces the low-frequency noise of traffic noise. Therefore, the low-frequency noise in the vehicle interior noise may come from vehicle body vibration.

From Figure 4.5, it can be seen that there is no obvious difference in the noise level of maintenance lanes of different types of roads in the middle and low frequency band from 125 Hz to 500 Hz. In the low frequency band below 125Hz, the noise level of the maintenance track of the road section with drainage and noise reduction in the long tunnel is less than that of the road section with dense gradation; In the medium and high frequency band above 500Hz, the noise of the maintenance road in the road section with drainage and noise reduction in the long tunnel is horizontally dense graded road section. The noise reduction effect is better because of the sound absorption function of the macroporous structure in the drainage noise reduction pavement.<br> It can be seen from Figure 4.5 that, unlike the noise inside the car, the spectrum distribution of the maintenance lane noise shows that the large gap pavement effectively reduces the medium and low frequency noise of traffic noise, so the low frequency noise in the car noise may come from the vibration of the car body.