Why can’t I sound like a native speaker?

You can thank your infant brain for that.

When first born, babies can distinguish nearly all speech sounds used in any human language. But by about 6 to 12 months, their brains begin to specialize, becoming highly sensitive to the sounds of their native language and less able to discriminate sounds that don’t appear in their environment. This process (called “phonetic pruning”) is essential for language development, as it helps babies focus on the speech sounds that are crucial for learning to speak and understand their native language(s) and ignore the speech sounds that are less important.

Once you’re an adult (even a teenager), the neural circuits for sound processing are less flexible and more committed to the phonetic categories of your native language(s). When adults learn a new language, their brains interpret unfamiliar sounds and patterns through the filter of their native language(s) system, making it difficult to perceive or produce the new language’s sound distinctions accurately.

As a result, adults rarely lose their foreign accent entirely, even after years of practice and immersion. Their speech tends to carry traces of their first language’s sound patterns. Having an accent does not indicate a lack of proficiency or intelligence. It’s because as babies, their brains worked hard to filter out the noise (literally) in order to learn language more efficiently.

References

• Kuhl, P. K. (2004). Early language acquisition: Cracking the speech code. Nature Reviews Neuroscience, 5(11), 831–843.

• Werker, J. F., & Tees, R. C. (1984). Cross-language speech perception: Evidence for perceptual reorganization during the first year of life. Infant Behavior and Development, 7(1), 49–63.

• Flege, J. E. (1995). Second language speech learning: Theory, findings, and problems. In W. Strange (Ed.), Speech perception and linguistic experience (pp. 233–277). Timonium, MD: York Press.

• Birdsong, D. (1992). Ultimate attainment in second language acquisition. Language, 68(4), 706–755.

• Golestani, N., & Zatorre, R. J. (2004). Learning new sounds of speech: Reallocation of neural substrates. NeuroImage, 21(2), 494–506.