Denise Van Lohuizen's ears have a cold nose.

Van Lohuizen, 26, who was born deaf, is the new owner of Heidi, a black, year-old, part German shepherd trained to alert her to sounds, including her alarm clock. Every morning Heidi pounces on her bed to awaken her with a lick.

"I need her also to alert me to someone knocking on the door, a smoke alert, a fire alarm," says Van Lohuizen a chambermaid, waitress and food preparer at a Stratton Mountain, Vt., ski lodge.

Heidi is a hearing-ear dog. She and Van Lohuizen have just completed the Hearing Ear Dog Program in Jefferson, Mass., near Worcester. It is one of a few programs in the country training dogs to become ears for their deaf masters.

In the United States today there are 16 million deaf and severely hearing-impaired people, plus an estimated 20 million others suffering from some degree of hearing loss. More than 50,000 live in the Washington metropolitan area. The deaf suffer from the invisible handicap. But no longer do they have to miss everyday occurrences -- a phone call, a baby's crying, a doorbell or a teakettle whistle. Trained hearing-ear dogs now alert many deaf people to these sounds.

Whereas seeing-eye dogs have been around since 1926, hearing-ear dogs are relatively new on the scene and have yet to receive the same recognition. Although detractors maintain that deaf people should not have to depend on a dog -- and should rely instead on family members and lighted mechanical devices -- proponents are enthusiastic.

"I don't oversleep," says Jack Kelly, 45, a computer aide with the National Cancer Institute. "If I pull the stem on my alarm clock, my dog Punkin a black Lab, one of the first to be certified in this area is right there in my face, with a wet tongue and a kiss. She's happy to see me wake up at 6:15 a.m. . I give her a hug and a treat."

Once Kelly was lighting a fire in the fireplace and within a few minutes, there was a smoke buildup, before the alarm went off. "Punkin pulled me outside, and I stayed there until the alarm went off. I wasn't going to chastise her because this is what she's to do."

Not every deaf person can benefit from a hearing-ear dog, says Donald P. MacMunn, the partially deaf director of the Massachusetts program. Among unsuitable candidates, he says: people with a fear or dislike of animals, those with unsupportive families or allegic reactions to dogs.

"We give priority to deaf mothers, those living alone and the elderly," says program administrator Sheila O'Brien. Currently there is a waiting list of 40 people who will have to wait six months to a year for a dog.

The Jefferson, Mass., program is believed to be the oldest and lowest-priced in the United States. Since its establishment in 1977, the nonprofit program, which operates on a $100,000 annual budget, has placed 180 dogs, including three with deaf-blind people. Recipients range in age from 6 to 84.

Clients must stay on the center's 90-acre farm for two weeks of intensive training. (Other programs send handlers to the deaf person's home for five to seven days of training.) On weekends the dogs go home with their masters to get acquainted informally, with an accent on play rather than school.

The client's cost, $150, covers all expenses, including room and board while at the center. The actual total cost of each dog's three- to five-month training is $3,000. Foundations and community-service groups such as Kiwanis, Lions and Quota clubs pay the $2,850 difference. Clients have come from 20 states, including Maryland, North Carolina, Florida and Wyoming.

Like most of the hearing-ear dogs, Heidi was rescued from a pound, in her case, Buffalo, N.Y. She passed the rigorous, 20-minute hearing-ear dog test for intelligence, curiosity, temperament, obedience and willingness to work. About 75 percent of tested dogs fail. Heidi also met the age requirement, eight weeks to two years. Most of the dogs are small- or medium-sized.

"No breed is better than another," says O'Brien. "In fact, most dogs are mixed breeds. Physically, mutts are stronger."

A teen-age Buffalo 4-H Club member trained Heidi in basic obedience until she was about 8 months old. "Kids are better trainers than adults," says O'Brien. "They are more tolerant; they don't expect as much."

Heidi was then passed on to the Massachusetts hearing-ear program for an intensive three- to five-month training program in which she learned obedience, socialization (with visits ranging from the shopping mall to an ice-cream parlor), response to sounds and sign-language commands. Most trainers are proficient in sign language.

Heidi and Van Lohuizen began their hearing-ear training with the "umbilical-cord treatment," in which dog and new master are tied together for two or three days during all waking hours. This technique transfers the dog's allegiance from trainer to new master, and "teaches the person that he now has a living responsibility," says Joan Adler, Maryland regional director of the program. "They become extensions of each other."

It is, however, acknowledges O'Brien, "a tiring and discouraging period for both."

"If the match doesn't work, we learn it at the center," she says. "We get more of a problem the first few days with dogs not liking people, but we really don't have that many problems. Training the dogs is the easiest part. The hard part is getting the person and the dog to work as a team."

Director MacMunn claims the training of dogs selected from the pound has a 97 percent success rate as compared with a 50 percent rate for training dogs that are already pets.

The program's staff matches dogs and owners after the prospective master completes a four-page application, which includes questions on the person's needs, living arrangements, history with dogs and the sounds for which the dog should be trained to alert his master. The dogs are conditioned to run repeatedly between the specific sound and the owner, touching him, until the master responds to the sound.

The dog usually is trained for six sounds. The most common: alarm clock, telephone (alerting the person to use his TTY, or telephone teletype), fire-smoke alarm, doorbell, baby's crying and teakettle. The dog also can be trained to respond to an emergency siren or car horn, for example, when his owner is driving. (The dog jumps into the front seat or paws his owner gently.)

"The dogs are not depressed working beings," says Joan Adler. "Training for sound work is positive." (Trainers reward the dog often and never punish it if it makes a mistake.)

"The dog is conditioned and approached in a positive, playful way," says O'Brien. "When a dog does sound work, he must love it."

"My dog kisses me each morning to wake me up," chuckles a Massachusetts hearing-dog owner. "That's more than my wife does."