The aim of our investigation was to address three questions: 1) does the phonological short-term memory capacity predict vocabulary learning outcomes; (2) does the phonological memory capacity vary across unfamiliar foreign languages; and (3) does language learning experience affect the phonological memory capacity? Thirty participants were tested before and after a five-hour language-learning course. We used nonword repetition tests with English, Russian and Indonesian-sounding words to measure phonological memory in these languages. We found that the phonological memory capacity in a specific language predicts vocabulary-learning outcomes in this language. Participants did not show a phonological bias toward a particular language, but homogeneously scored higher on the Russian nonword repetition test. All participants improved on nonword repetition tests across all languages after learning either Russian or Indonesian. These findings support the following conclusions. First, nonword repetition tests in specific languages can be used in aptitude batteries to detect a propensity for these languages. Second, individual bias towards the phonology of a specific language is rare and gets overridden by the phonological distance between a mother tongue and a target language. Third, phonological memory is affected by language experience and this effect can be transferred to other languages, including L1.