* Very slight buffering from wind and cold: A thick head of hair can act as a minor barrier against wind, which might slightly reduce the wind chill effect on the ears. It offers a tiny bit of insulation against the cold.
* Minimal debris protection: Hair might catch a few very large particles of dust or debris before they reach the ear, but this is negligible.
Important Note: The primary protection for the ears comes from the structure of the ear itself (the concha and ear canal) and in some cases, earwax. Hair on the head is mostly for warmth and sun protection for the scalp.