Babies must separate the phonemes from the allophones.
The /t/ phoneme in English is actually four different phons. They are as follows:
- The aspirated /t/ as in "take."
- The unaspirated /t/ as in "steak."
- The unreleased /t/ as in "cat."
- The nasaly released /t/ as in "cotton."
You could use them interchangeably in the word "cotton" and it would still mean a piece of fluff.
Sounds that are different, but are accepted as the same phoneme in a language are called allophones. In English those different /t/ phons are allophones.
In some other languages, the degree of aspiration changes the meaning and hence the ÑtÅs would be considered phonemic.
Babies certainly have their work cut out for them, to separate the phonemes from the allophones! It truly is a job that separates the men from the babies.