Baby not responding to my name calls all times

6.5m old doesn’t turn back when I (mom) call him but comes crawling to me when he feels like , otherwise just ignores me. Whereas every time my MIL calls him, he turns back & smiles at her. Apart from this , he gets highly startled whenever he sees a moving vehicle / someone switches on the noisy mixer grinder at home / turn on the TV.

Is something wrong ? Why is he like ignoring me ? And why those high startle reflexes ?