Rabi'ah (may Allah have mercy on him) said that if the faculty of hearing is lost entirely, there is the full diyah for it; and he said that if the hearing of one ear is lost, there is half the diyah. And Makhul (may Allah have mercy on him) said that if the faculty of hearing is lost, there is the full diyah for it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16227