How long will accent modification take?
Boy, I wish I could answer that!
How long accent modification will take for you depends on so many individual variables, including:
Your goals. Do you want to learn to produce a few target English speech sounds to increase your intelligibility (how well people understand you)? Or do you want to master subtle English speech patterns to increase your naturalness (how much people notice your accent)? Is your priority short-term preparation, like an upcoming interview, or long-term development of your communication skills?
Your current speech, which also depends on many factors, such as your native language(s), the age you began learning English, whether you learned from a native speaker, and how much immersion and accent instruction you have had.
Your commitment to practicing new skills outside of 1:1 coaching. Practice is important!
Your availability to schedule regular sessions. Between work and life, everyone is busy, so this can be difficult. But consistency makes a big difference in how long it takes to reach your goals.
One factor that absolutely does not affect how quickly you reach your accent goals is intelligence. You've learned another language well enough to live, work, and communicate in it every day. That’s incredible. Accent change is about building new habits, not how smart you are.
What I can predict is this: if you’re consistent and committed, you will see change.
Supportive research:
MacWhinney, B. (2017). Working memory and second language acquisition. E-Learning Papers. https://eprints.whiterose.ac.uk/id/eprint/144769/
Flege, J. E. (1999). Age of learning and second language speech. In D. Birdsong (Ed.), Second Language Acquisition and the Critical Period Hypothesis (pp. 101-131). Lawrence Erlbaum Associates.
Babel, M. (2012). Evidence for phonetic and social selectivity in spontaneous phonetic imitation. Journal of Phonetics, 40(1), 177-189. https://arxiv.org/abs/2502.01210
