Muʾallalatān is a feminine dual. Its root ʾ-l-l relates to a fine or sharpened point; in this context the ends of the ears are thin and pointed, not necessarily large or loud.
Al-ʿitq denotes excellence or nobility. In tuʿrafu al-ʿitqu fīhimā, the shape of the ears is treated as a recognizable sign of good stock. This is the cultural and literary claim made by the passage, not a modern scientific statement about inherited traits.