hearing dog(n = noun.animal) - dog trained to assist the deaf by signaling the occurrence of certain sounds;
is a kind of working dog

administrative hearing, african hunting dog, african wild dog, american dog tick, american dog violet, attack dog, badger dog, bernese mountain dog, bird dog, blacktail prairie dog, bottom dog, cant dog, cape hunting dog, carriage dog, chili dog, chrysanthemum dog, coach dog, colored hearing, competence hearing, conductive hearing loss, confirmation hearing, crab-eating dog, curtail dog, devil dog, dirty dog, dog, dog bent, dog biscuit, dog bite, dog breeding, dog catcher, dog collar, dog days, dog do, dog eared, dog fennel, dog flea, dog food, dog grass, dog hobble, dog house, dog in the manger, dog laurel, dog mercury, dog paddle, dog pound, dog racing, dog rose, dog shit, dog show, dog sled, dog sleigh, dog star, dog stinkhorn, dog tag, dog tired, dog turd, dog violet, dog wrench, domestic dog, eskimo dog, fair hearing, gay dog, german police dog, german shepherd dog, great dog, guard dog, guide dog, gun dog, hair of the dog, hearing, hearing aid, hearing disorder, hearing examiner, hearing impairment, hearing loss, hearing officer, hot dog, hound dog, hunting dog, hyena dog, iditarod trail dog sled race, little dog, mad dog, maltese dog, monkey dog, newfoundland dog, organ of hearing, pariah dog, police dog, poodle dog, prairie dog, raccoon dog, red dog, sausage dog, sea dog, seeing-eye dog, seizure-alert dog, sense of hearing, sensorineural hearing loss, shaggy dog story, sheep dog, shepherd dog, shetland sheep dog, sled dog, sledge dog, spitz dog, sporting dog, top dog, toy dog, water dog, whitetail prairie dog, wild dog, working dog