The Strange Persistence of First Languages (2015)
nautil.us
nautil.us
My (uneducated) guess is that the parts of the brain that are responsible for learning in the young age are not the same as those that we use when we grow older, which are perhaps less efficient. This is somewhat disconcerting, because it gives rise to other questions, such as whether other types of learning and mental activity in general may also be affected by the relative inefficiency of the neural mechanisms we are left with at a later age.
I don't think I believe that it's actually impossible though, at least not for everyone. What seems more likely to me is that for most people it's just not necessary or practical to become 'accentless', or at least it's not perceived to be worth the effort or money (for a vocal coach, or something like that).
A child not only has a brain that is (probably) optimized at that point in time to learn languages, but a child also has the privilege of being immersed in the language to learn, as well as massive amounts of free time to do so. Not to mention a lack of shame of messing up (or judgment for doing so).
Feynman once observed in his autobiographical "Surely You're Joking Mr. Feynman" that most of it comes down to being willing to make completely foreign sounds.
On the other hand, I have a soft Austin, Texas accent. As the state capitol and a bit of a tech city, it actually consists mostly of immigrants but my family had been in the area for sometime, and knew other families that had been in the area for some time, so I can hear a "native" Austinite accent that most people probably wouldn't even be aware exists, because of how out-numbered the "natives" have become since the 60s or 70s. It's a little southern-tinged with a bit of "breathy" sound, and not very strong (not very markedly different from a "neutral" US accent), but pins down a pretty distinct region if you've heard it enough. I sort of trained it out of my voice around age 12 by emulating people on TV. At the moment, I cannot consciously speak with that accent. I don't even know how to, and I don't live in the area anymore, and I can't do a voice with that accent in my head, but do know it when I hear it. Under a lot of fatigue or stress, I sometimes actually start speaking with that accent, which seems strange, because I can't consciously make myself do it at any time. I couldn't consciously do it properly on command for a million dollars right now.
> willing to make completely foreign sounds
I am afraid this may be not enough - it seems that we lose a perfect Fourier analyzer (and synthesizer) built into our brain at an early age.
Czech language is one the most beautiful slavic languages, I love hearing it even if I don't understand a lot, it is joy for my ears.