A series of experiments were conducted to examine the behaviour of Japanese-speaking learners of French (JSL) concerning the perception and production of the French /u/, /y/ and /ø/, in order to examine how L2 (second language) vowels which do not have phonemic and/or phonetic equivalents in L1 (native language) are acquired by learners. The results indicate that JSL tend to produce the French /u/ with a high F2 (> 1000 Hz), which is heard as /ø/ by native French (NF) listeners. They suggest that the French /u/ is considered by JSL as phonemically similar to Japanese /u/ (as a high non-front vowel) and produced as such, while the phonetic realization of the French /u/ is new and different ; and that /y/ is considered as both phonemically and phonetically new, and /ø/ as phonemically new but phonetically (acoustically) similar. Phonemically similar but phonetically new vowels seem to be most difficult to learn to produce accurately for foreign/second language learners.
