I read this terrific article on the Writer's Digest website. It said that suspense is created when nothing else is happening. Think about it--the girl is standing in the hallway, looking at the light coming from the crack under the door. The room beyond should be empty...and then something blocks the light. We wait and--
That's suspense. Nothing is happening, but we know something is going to happen. TV shows do this all the time. I remember one episode of House where a guy in a wheelchair starts to cross a dark street and has a seizure. The chair stops moving. His therapy dog barks and pulls at him, trying to rouse him.
A driver drops her cellphone and dives for it.
The man slumps in his wheelchair in the middle of the road.
The dog barks desperately.
The driver sits up, sees the man and dog, and swerves wildly--
I guess things, plenty of ordinary things, are happening in this scene. Put them together and they build tension. It's the combination that makes it suspenseful--if the guy had a seizure on the sidewalk, if it had been broad daylight on a crowded street, if the driver hadn't been distracted, there would be no suspense.
The barking dog adds a very nice touch of urgency--for all we know, the man is going to die anyway. But the dog won't leave him and it's a rule universally acknowledged: DON'T HURT THE DOG. People hate that.
But we love suspense. We love the sensation of dread, of hope, of holding our breath until the danger passes or arrives with a scream.
We love the emotion, the rollercoaster ride of sensation. That's why we read, and that's why I write.