There is often a relationship between perception and production in second language acquisition, depending on phonological transfer from the speaker’s first language (L1). In a production study of Karen speakers learning Swedish as their second language (L2) it appears that they have difficulties learning the pronunciation of Swedish, especially final stops. In order to find out if Karen speakers perceive phonological contrasts in Swedish words produced by a Swedish native speaker, a perception test was constructed. The results indicate a phonological transfer from L1 to L2. Another observation is the role of age during second language acquisition.