elijah cook was found to be profoundly death in his left ear and only able to hear 75 decibels in his shortly after his birth in january .
the mothers and fathers of both his parents , ahavah and jason cook , of andova , minnesota , were all deaf , so doctors decided to press ahead .
last month they fitted elijah with a set of hearing aids .
the moment he responded to his mom 's voice for the first time was caught on video , with elijah clearly responding .