It is well established that early bilinguals can accurately produce and perceive sounds in both of their languages (e.g. Flege and Eefting, 1987, Sundara, Polk, and Baum, 2006; but see also below). This applies both to sounds that occur in only one of the two languages and to sounds that are common to both but differ at the phonetic level. For example, the trilled /r/ in Spanish and the approxi...