This study investigates how second language (L2) listeners' perception is affected by two factors: the listeners' experience with the target dialect -- North American English (NAE) vs. Standard Southern British English (SSBE) -- and talkers' language background: native vs. non-native talkers; i.e. interlanguage speech intelligibility benefit (ISIB) talker effects. Two groups of native-Korean-speaking listeners with different target English dialects -- L1-Korean listeners of English as a second language (ESL) in the USA and L1-Korean ESL listeners in the UK -- were tested on the identification of 12 English vowels spoken by native and non-native (L1-Korean) talkers of NAE and SSBE. The results show that the L2 listeners' experience with the target dialect had a significant impact on the accuracy of their identification of the L2 vowels. However, no ISIB-talker effects were observed for the L1-Korean listener groups regardless of the listeners' differences in experience with the two varieties of English. The study adds to the L2 sound acquisition literature and the ISIB literature by looking into L2 learners' identification of L2 vowels, taking into account the learners' differences in experience with two standard varieties of English (NAE and SSBE) and the interaction between the learners' experience with the two varieties and ISIB-talker effects. It also sheds some light on the issue of adult L2 learners' ability to learn the vowels of a new target variety.