This study evaluated whether age effects on second language (L2) speech learning derive from changes in how the native language (L1) and L2 sound systems interact. According to the "interaction hypothesis" (IH), the older the L2 learner, the less likely the learner is able to establish new vowel categories needed for accurate L2 vowel production…

Although spoken language is communicated via a rapidly varying signal, human listeners recognize spoken words both quickly and accurately. Nonetheless, variability in speech does have implications for both the processes and representations involved in spoken language perception. Moreover, variability effects have been observed across the lifespan,…

Behavioral studies have shown that while young infants can discriminate many different phonetic contrasts, a shift from a language-general to a language-specific pattern of discrimination is found during the second semester of life, beginning earlier for vowels than for consonants. This age-related decline in sensitivity to perceive non-native…