In modern society, urban noise problems are becoming incrreasingly serious due to industrialization and urbanization. The government is operating a passive environmental noise measurement network in accordance with the “Environmental Noise Measurement Network Operation Guidelines” to determine the noise status. Since the noise sources are diversified due to urbanization and each of them has specific characteristics, it is necessary to observe the perceived noise level through frequency and Traffic Noise Index (TNI) analysis, as well as quantitative evaluation such as environmental noise verification of the source. In this study, noise levels were measured a total of six times during the day and night semiannually in Gwangyang and Suncheon cities in Jeollanam-do, and frequency and TNI analysis was conducted for the areas that exceeded the standards. The results are as follows. Gwangyang City showed an excess rate of 0.8 to 14.3% compared to the noise standard in school areas and general residential areas, and showed high noise levels in the high-frequency area near 1 kHz due to the influence of traffic. Among roadside points in school areas and general residential areas, 83.3% of all points showed TNI index exceeding 74. Suncheon City showed an exceedance rate of 2.7 to 17.8% in green areas, and showed high noise levels at high frequencies around 1 kHz and around 250 Hz due to the influence of vehicles and motorcycles. Additionally, the TNI index of green areas exceeded 74 in all time zones except midnight. We expect that the results of this study can be used as basic data for improving measurement network operation and establishing noise reduction measures in the future.