Worried

So my baby was born at 31 weeks, he’s 6 months but 4 months adjusted, my worry is that he doesn’t seems to turn toward voices/sounds? He passed his hearing test while in the NICU, & he gets startled by loud sounds, he smiles & coos a lot & also turns to look at me if he’s laying down & I’m walking across the room, but whenever I clap or start talking to get his attention he won’t turn to look for me, I can only get his attention by getting into his view, only then will he pay attention. Idk if this is normal & I’m just over reacting. I’m a first time mom & I can’t help but stress about his development since he’s already delayed due to being a preemie. Are your babies doing this? TIA ❤️