What do you think about this? In addition to the emphasis that distinguishes the non-native speaker of the native speaker is a sound (music) words. Because many of those who know or learn another language pronounce words clearly, but they speak in their national sound / tone. And it is seen. А сhild first learns/remembers the sound of words with a subject association before they will learn grammar. That adults spend very long time to understand the words / grammar. But as soon as we start talking we have an association of grammar, not the words with the sound.