What interesting facts about a cat's hearing and sense of smell!! It is humbling to know that when we speak to them and get no response that we are simply being ignored! I have also seen both of them twitch their little noses up in the air when, to my nose at least, there is no odor present. I think their vision is probably right up there with their other excellent senses. Mine seem to be able to spot a tiny bug on a wall from across the room. Before I can actually see the bug myself I see the tail whipping and the fixed stare on their little faces. Aren't cats just terrific!!!