This study reviews the two types of tonal change recently found in contemporary Seoul Korean. The first is the emergence of tones according to the onset at the initial syllable of the accentual phrase. This phenomenon synchronizes the overlapping process of Voice Onset Time (VOT) distribution between lax and aspirated obstruents. Several previous studies have indicated that this dialect is in the middle stage of tonogenesis. The second type of tonal change is the emergence of the H tone in the word il, meaning “one.” The present study examines the possibility of interpreting the two phenomena as lexical diffusion.