This paper examined whether a younger starting age of formal instruction on a foreign language is beneficial in expanding circle countries. An experimental study was designed to examine to what extent the five varieties of English language teachers are intelligible to Japanese- (JSLs) and Korean-speaking language learners (KSLs), who have different starting ages of formal English education. First, 132 JSLs and 214 KSLs participated in a listening test where the accents of audio stimuli were varied. The results showed significant differences in the listening test scores between the two groups of learners and among the five varieties of English. It was found that KSLs who started learning English language at an early onset demonstrated proficient listening performance. These findings provide support for the premise that "younger is better" in development and persistence of L2 sound identification. At the same time, both JSLs and KSLs demonstrated sensitivity to input varieties of English. This highlights the importance of exposing students in the classroom to various English accents that may encounter in real-world situations.