As with hearing dogs for the deaf, the dogs may be trained to alert their handler to important noises or other things requiring human intervention, such as smoke or a smoke alarm, a crying baby, a telephone ringing, or a knock at the door. For a person with autism, it may not be immediately obvious which of the many external stimuli is the urgent one requiring their immediate attention. A person with autism may have to sort through both major and minor stimuli—the sound of crickets, the smell of the fabric softener on their clothes, a car driving past outside—to determine which of these, if any, needs their attention. They may understand that a smoke alarm is urgent and requires them to exit the building, but it might take more time to realize the alarm is sounding in the first place.
