As your baby begins to pay more attention to what's going on around him, he may develop new fears. He may suddenly cry and cling to you when he hears even familiar sounds, such as a dog barking next door, the vacuum cleaner or the doorbell. This is a normal developmental stage, so don't be too concerned. Just comfort your baby by giving him lots of hugs and kisses. This will reassure him that you're nearby and all's right with the world.