How long might a native English speaker (from California) retain some detectable Russian accent after returning to the USA, after spending 6 to 7 years speaking (and exposed to) nothing but Russian?
I know some people 'carry' accents for a while that they are exposed to for any length of time (I used to be one). My google-fu is mostly returning articles on Foreign Language Symptom, which is not what I want. (And I the only one who hates Google's new search algorithm?)
His Russian, of course, is spoken with an American accent, but I'm not concerned with that. My character needs to be mistaken for a Russian by someone who knows nothing about him but what he can see and hear. How soon do they have to meet after my character gets back? How long before there isn't likely to be any Russian accent left? Is there anything that would reduce or lengthen the time span?
Setting is current-ish, so travel time isn't a factor.