3.5 month old not responding to sound

Stephanie • Married 2 years, 4 baby losses. Jun 2017, chemical. Dec 2017, missed miscarriage. Jul 2018, ectopic, lost left tube. Nov 2018, missed miscarriage.

I’ve noticed that my 15 week old doesn’t turn when I walk into his room calling his name. But when he’s looking at me, he babbles back when I talk to him and I’ve seen him flinch with loud noises. Is this cause for concern? I’ll be asking his pediatrician at his 4 month appt, but just curious what it’s been like for other babies