I hear that.

I hear that he says to me.  We are outside and I point out to him that it is a airplane and I hear it too.  He says Airplane and looks up in the sky to find it.  Eventually he points and shows me where it is.

I hear that he says to me.  We are standing in line at a small convenience store.  We hear ding dong, ding dong.  He doesn't know what's making that noise.  I point to the door and explain the door makes that noise every time the door is opened.  He's fascinated with this explanation and watches each time another person opens the door.

I hear that he says to me.  We are in the parking lot walking into the grocery store.  I tell him that sound is a car's horn honking because someone is locking their doors.  Honk Honk.  He gazes around the parking lot looking for the particular car making the noise.

I hear that he says to me.  We are inside our house, sitting in the kitchen eating a snack.  I hear it too and tell him that sound is the heat rattling through the vents and the furnace downstairs.  This seems a little complicated for him but he looks like he's pondering the explanation and doesn't ask anthing again.