Detecting noises and sounds

Hello parents, at which stage will babies be able to detect noises and respond? Also, what are some of the things to look out for as for his hearing? Currently my child is 2 months+. He has passed his initial hearing test conducted by the hospital. During his subsequent visit to the clinic, he seems to have little to zero interest in responding to the bell sound when doctors attempt to do a hearing test. Should I be worried or if this is normal?#firstbaby