The hearing dog is a service dog trained to assist deaf and hard-of-hearing people to cope with the surrounding sounds they do miss out. Particularly for those individuals who live alone or in households where there are no hearing people, it can be important that they be alerted to certain occurrences needed to be alerted at. People with a hearing loss travelling alone on might feel safe with an assistance dog who also will react to signals trained for; an approaching car, tram or bicycle from behind; an announcement in train or at station.
The hearing dog alerts to different stimuli in the home but outside as well. The hearing dog has a sound alerting and constant companion dog role first and eventually public access and protection role, which depends on the partner.

A hearing dog has been specially trained to listen for these sounds, humans (and dogs!) take for granted. The trained dog can tell when a sound occurs and will show where it's coming from. Dogs can be trained to respond to the listed few possible tasks:

ALERT TO SPECIFIC SOUNDS AT HOME

• Doorbell ringing
• Knock on front door
• Rapping on patio door or window
• Smoke alarm sounding
• Wind up minute timer, oven or microwave timer going off
• Baby crying
• Family member or other calling the name of the dog's partner
• Child calling "mommy" [or other name, if applicable, such as daddy, grandpa, aunt]
• Phone ringing
• Alarm clock buzzing
• Computer equipment beeps
• Horn honking in garage or driveway
• Arrival of school bus

ALERT TO SPECIFIC SOUNDS AWAY FROM HOME

• Siren of police car, fire truck or ambulance and indicate direction
• Smoke alarm in workplace
• Distinguish phone ringing on partner's desk at work from all other phones in workplace
• Name of partner if coworker, friend, family member calls out that name
• Cell phone or beeper
• Smoke alarm in hotel or work
• Fire drill at school or work
• Vehicle honking to attract attention

OTHER POSSIBLE TASKS

• Retrieve unheard dropped objects like keys , coins, or other objects
• To enhance security when the team arrives home after dark, the dog enters the home first to turn on a light, nudging the metal base of a lamp with a touch lamp device
• Carry a note from the partner to another household member, searching the house to find that individual
• Carry messages between spouses, utilizing objects which signify dinner is ready or that the person needs help right away, and so forth.
• Have the dog find and return with the hearing impaired person.
• Warn of a vehicle approaching from behind, or making a sudden turn. A task that applies the intelligent disobedience principle to hearing dog work

Hearing dogs are trained to react to different sounds or situations. The alert can be one way. Alert the partner and remain there: alert on an alarm clock in the morning and wake up the partner. Here's no need to have the dog show the source of the sound. The alert can be a two way alert. Alert the partner and guide to the source of the sound: alert on name call or doorbell, etc.

The two-way alert is informative but hard to teach for many different sources possible. The alert to the partner can be a simple touch, a rough push, barking or even spinning around, as long as the alert is specific and attentive. The type of the alert depends on the dog but also on the partner. When the partner ask: "where is it?, the hearing dog brings the handler to where the sound is coming from. When the doorbell rings or a knock on window the dog is not taught to bark at this sound, although some dogs will bark as a natural response to the "intruder" at the door or window. Instead, the dog is trained to run to find her owner, give alert and then run back to the source on command. This visual response leads the person to the location where the sound is happening.

A hearing dog it's function doesn't limit to sound alert for capacity of the dog can be more complex. Picking up lost articles is something hearing dogs can perform for handlers. Some dogs can have another function added just like protection roles or just sport to extend social life. Depends on what the individual handler is looking for. Each dog also receives obedience training in the basics of heel, sit, down, stay and come. Sign language can be used; the dog is trained to respond to all obedience commands by signal as well as voice.

A dog as companion is another thinkable function which is something we don't have to train dogs for: this is natural inherited in dogs. Handlers only do have to warm up the dog for that extra function.