## 1 Introduction
Additionally, research has been conducted to develop a new rating factor to quantify and evaluate low-frequency impact noise [12; 13]. Latex-modified concrete undergoes changes in properties based on the water-cement ratio, aggregate-cement ratio, and polymer-cement ratio, making it necessary to design mixes suitable for the intended purpose. In latex-modified concrete, the polymer-cement ratio has a more significant influence on its properties than the water-cement ratio, which typically determines the properties of ordinary concrete [14]. The polymer-cement ratio is expressed as the mass ratio of the total solids content in the polymer admixture to the cement. The water-cement ratio is determined by the required workability, such as slump or flow values. Generally, the water-cement ratio calculation includes both the moisture in the polymer admixture and the amount of added water. It is desirable to keep the water-cement ratio as low as possible, within a range of 30-60%. Typically, the polymer-cement ratio ranges from 5 to 20%. As the polymer-cement ratio increases, properties, such as tensile and flexural strength, adhesion, impermeability, chemical resistance, abrasion resistance, and impact resistance, improve, but surface hardness decreases. In latex-modified concrete, the cement hydration process forms a binder that connects the aggregates. The latex strongly bonds with the hydrated cement particles, forming a polymer-cement co-matrix with a network structure. Meanwhile, research has been conducted to use SBR latex as a sound insulation material for floor impact noise. To determine the proper mixing ratio of mortar with SBR latex, changes in compressive and tensile strength and floor impact noise were observedfor each mortar curing time. The results showed that floor impact noise was reduced when 5% of SBR latex was mixed into the mortar. Specifically, a reduction of about 2-3 dB in floor impact noise at 125-500 Hz was achieved when a tapping machine was used, and about 2-4 dB at 125-250 Hz with impact balls. It was also found to be very effective in reducing vibration. When vibration was measured from the bottom of the slab on which the SBR Latex mortar was installed, the impact was reduced by about 3 to 5 dB in the 500 Hz to 1 kHz band when using a tapping machine. When a bang machine and impact ball were used, floor impact noise was reduced by 1 to 3 dB in the 63 Hz to 1 kHz band [15; 16; 17]. Additionally, floor impact noises were measured using mixed SBR latex mortar, with admixtures having various glass transition temperatures. The results showed that mortar containing only SBR latex with a glass transition temperature of \(-11\,^{\circ}\)C exhibited the highest dynamic modulus of elasticity and the greatest reduction in floor impact noise [18; 19]. In general, it is most effective to reduce impact noise near the point of the noise source. Since the mortar layer commonly lies just beneath the floor finish, it is expected to be highly effective in reducing floor impact noises. The present study aims to identify the reduction characteristics of light- and heavy-weight impact noises by examining changes in mortar strength after mixing SBR latex.