Ray Dobson and the dog he now calls Goblin both had a problem.

The little mixed breed who was rescued from the streets of Puerto Rico needed a home. Dobson, of Orleans, Mass., was losing his hearing.

"My wife saw me kind of dropping out," he says. "As people get deafer they get more anti-social."

Both problems were solved when man and dog were brought together by the National Education for Assistance Dog Service, which trains dogs from shelters to assist the hearing impaired. The organization, which is based in Princeton, Mass., has placed more than 1,300 hearing dogs all over the country since 1976.

Goblin does for Dobson what his digital hearing aid can't.

"What the dog does for me is hears what I can't hear," he says. "She can hear the phone ringing, alarms, knocking on the door, when people call my name."

The dogs chosen for this job have to have special qualities — often the qualities that land them in shelters.

"The hearing dog is usually the dog no one wants," says Brian Jennings, who has been a trainer at NEADS for 20 years. "It's usually hyperactive, willful, compulsive. They have to be. If the dog wakes you in the middle of the night because the smoke alarm's going off and you push them away, they have to not give up."

What's unique about hearing dogs, says Kathy Foreman of NEADS, is that they work without being given commands. A guide dog for the blind, for instance, is given a command to go forward, and, while it knows to disobey if there's danger, it's still initially responding to the handler's direction. Hearing dogs, by definition, need to do their work when their owner doesn't know there's a job to be done.

So trainers look for dogs who are curious about sounds, but also very confident. These may be exactly the dogs that drove their original owners crazy because they were bouncing off the walls, but as Jennings observes, "sometimes a dog's weakness is its strength."

The dogs are trained to touch the owner and lead him physically to the source of certain sounds. So that they'll do this on their own initiative, Foreman says, the secret of training is to make the dog think "it's a big game, and we are happy to play it with you any time."

New owners are taught how to keep the dog's skills sharp, such as praising it for responding to sounds even in cases that turn out to be unimportant.

NEADS has no physical requirement for hearing dogs. "We've had everything from Chihuahuas to German shepherds," Jennings says, and most of them are mixed breeds.

Hearing dogs not only let their handlers know that they've dropped their car keys, but also help in less tangible ways. Social interactions are often affected since deafness is not a visible disability. Foreman says that not hearing when your name is called is a big issue for the clients: "People say, people at work thought I was the biggest snob because I ignored them."

The dog not only helps make the handler aware of sounds, but makes observers aware of the handler's situation.

"When they see the dog, it helps people understand that they need to take extra time to communicate with that person," says Jeanine Konopelski of Canine Companions for Independence.

For the hearing impaired, the dogs allow more freedom and independence, says Robin Dickson of Dogs for the Deaf in Oregon. A client said that before she had a dog, "I never had time to think, because I was always trying so hard to listen."