###### Abstract
demonstrated mechanically coupled resonators to design a particular transmission loss with a wider bandwidth of attenuation. An analytical model was developed for a single coupled resonator mounted on a one-dimensional duct, and experiments were conducted to measure the transmission loss of a coupled resonator system with the membrane. Both analytical and experimental results verified that the transmission loss could be modified by varying the properties of the coupling member [8]. [PERSON] et al. experimentally studied the effects of two coupled cylindrical Helmholtz resonators on the sound absorption performance. Their study presented that the coupling by the cavity compartment could improve the sound absorption capacity and the front resonator should have a weaker acoustic resistance for optimal design. They also concluded that a relatively small cavity of the rear side compared to the original cavity could significantly widen the frequency band without affecting the sound absorption [9]. [PERSON] et al. investigated the wave propagation in the periodic ducted HR theoretically and numerically. The transfer matrix method for the theoretical analysis was developed and compared with the FEM analysis result. Their results showed that both the noise attenuation band and peak amplitude were increased by adding HRs [10]. [PERSON] et al. proposed a new analytical model to calculate the resonance frequency of a Helmholtz resonator with multiple necks considering leaks inside of the resonator as additional necks. They compared their explicit formula with experimental data available in the literature and showed that even small holes in the resonator might lead to a significant increase in the resonance frequency and a considerable reduction in the absorption performance [11]. Although many studies and analyses have been conducted to draw a solid conclusion regarding the relations between resonance frequency and geometric sizes of the cavity and orifice, the complete design practice to obtain a precise resonator matching the resonance frequency at a specified frequency still has not been presented. Thus, many researchers have conducted studies to achieve noise attenuation capacity for their application fields with varying geometric and array configurations [12; 13]. In summary, most researchers combine theoretical, numerical, and experimental methods altogether to develop and validate new sound attenuation devices, such as intake and exhaust systems of automotive and jet engines and combustors. In this study, a slit-type HR is conceived to provide low-frequency sound attenuation and air-transpassing capacities for a soundproof panel. With the rapid increase in automobiles, the importance of noise pollution reduction is emphasized to provide a comfortable environment in urban areas, and soundproof panels are used to alleviate noise levels along traffic roads. Although many soundproof panels have used sound-absorbing material to reduce low-frequency noise, its capacity has gradually deteriorated due to the blockage of small holes in the material, and as the height of the urban space increases, it is necessary to reduce the wind load for the construction of higher soundproof walls. The design concept of the soundproof panel proposed in this study reduces the magnitude of the wind load with air-transpassing slits provided in the panel while maintaining traffic noise reduction capacity using the HR. By reducing the magnitude of the wind load, it is possible to construct a higher soundproofing wall more economically. To effectively minimize traffic noise, the resonance frequencies are designed for low-frequency noise attenuation. Both numerical and experimental methods are utilized in developing a slit-type soundproof panel, similar to the methods of most researchers.