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| Ask any dog owner why his or her dog barks and you'll get a plethora of answers. Because he is hungry. He wants to come inside. He can't stand strangers on his property. With so many uses for one type of vocalization, is barking just a nuisance by-product of domestication or could barking serve some specific communication functions? |
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For the answer, I initially turned to the scientific literature. Surprisingly, although there are over 52 millions dogs in the U.S. alone, there are very few studies on vocal communication in domestic dogs. The two main peer reviewed papers were published in the 1960s and 1970s and a well-known popular press article was published in the early 1990s. Most books, textbooks, and scientific articles that mention barking in dogs cite these three sources. Interestingly, the consensus among researchers has been that dogs bark so frequently, in so many contexts, and some bark for such long periods of time in the absence of obvious stimuli or receivers (animals that are listening), that barking must just be a non-specific way for dogs to get attention. More subtle communication occurs through body language and olfactory cues. |
| These arguments are convincing, especially in light of the fact that barking is often considered a nuisance behavior. Many counties in the U.S. have adopted ordinances that address noise from barking dogs (Seen and Lewen, 1975), barking is a major source of noise pollution in dog kennels (Sales et. al., 1997) and inappropriate barking is one of the most common behavior problems that owners report to their veterinarian with up to 35% of owners listing this as a complaint (Beaver, 1999) |
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| These arguments are, however, the types of arguments reserved solely for domesticated animals. Because it's easy for people to assume that such animals are tainted by a soft life and artificial selection and thus have many aberrant or functionless behaviors. If however, we take a step back and evaluate vocal communication in domesticated dogs the way we would evaluate vocal communication a wild animal the view becomes quite different. |
| Vocalizations in Wild Animals Many wild animals use one vocalization frequently and in many different contexts and some repeat one or more vocalization for hours on end. In cases where a species uses one vocalization in many contexts, researchers have found that upon closer evaluation, the vocalization is actually comprised of subtypes. For instance, chacma baboons bark in several contexts (Fischer et al., 2000). Their alarm barks made when they see predators is acoustically different from the contact bark they make when separated from their group or from their offspring. Additionally, the alarm barks they make towards mammalian predators is different from those made towards crocodiles. |
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Other animals have been known to vocalize for many hours in a row. The classic example is the song bird who sings sonorous songs in spring. These birds sing in order to protect their territory and to attract mates. Females are attracted to the males with he best songs. Even wild canids have been known to vocalize for hour upon hour. During breeding season, wolves may howl and howl without reply (Field, 1975). These vocalizations are to attract females from neighboring packs.
In light of these findings in wild animals, there are many reasons why barking could be a specific from of communication in dogs. As a first step towards exploring this topic, I embarked on a study that asked the question, "Are barks context specific?" That is, are barks in one context acoustically different from those in other contexts? |
 I took ten adult dogs of six different breeds and recorded barking in three different test situations-a disturbance situation where a stranger rang the doorbell, an isolation situation where the dog was locked outside isolated from its owner, and a play situation where either two dogs or human and dog played together. Using a sound-editing program, I then converted the digital recordings of 4672 barks to visual displays called spectrograms. A computer macro written by Dr. Brenda McCowan (Department of Population Health & Reproduction, UC Davis, bmccowan@vmtrc.ucdavis.edu) took 60 sequential frequency (pitch) measurements and 60 sequential amplitude measurements along the length of each bark and then recorded values such as minimum, maximum, mean frequency, start slope, finish slope, frequency range, amplitude range, bark duration and interbark interval for each bark. |
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 Can you interpret dog barks? Take the test! Download and play the following six barks and guess whether they occured in the disturbance context, the isolation context, or the play context. Bark 1 | Bark 2 | Bark 3 | Bark 4 | Bark 5 | Bark 6  |
Findings Statistical analysis revealed that dog barks can be divided into different subtypes based on context and that individual dogs can be identified by their barks. Additional analysis revealed that disturbance barks tend to be harsh, low-frequency, and unmodulated whereas isolation and play barks tend to be tonal, higher-frequency, and modulated. These findings suggest that barks may have specific functions in specific contexts; further studies should be performed to explore this idea. Additionally, because barks vary predictably with context, humans should be able to recognize the barks their dogs give in specific contexts. Doing so will give humans a better understanding of dog behavior in general as well as help in diagnosing and treating bark-related problems. |
| How can you
learn to understand what your dog’s saying? You can easily learn to interpret your own dog’s barks by carefully listening and noting the context, his body posture, and the response of the listener. For instance, listen to your dog’s bark when a stranger knocks on the door. Is it harsh like your voice when you have a cold or clear so that is sounds like a single note? It is low pitched or high compared to his other barks? Does it occur in clusters with many closely spaced barks or are they single barks? Are the barks so fast their fused into superbarks? Now listen to your dog’s barks in other situations. Do the barks to strangers at the door sound the same as those to friends who come over? When Bowser’s barking at squirrel outside is it the same as his bark for his toy? By systematically looking at the specific contexts and correlating it to what you hear, you’ll quickly be able to interpret Fidos specific barks. |
After
months of hype, the Bow-lingual, a gadget that claims to translate
dog barks into English,
is finally on the market. Manufactured by Takara, a Japanese toy company,
this device listens to a dogšs barks and then
categorizes the dogšs mood as happy, sad, onguard, assertive, frustrated,
or needy. Each emotion comes with one of 178 cutesy English-sentence
translations. |
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Popular Press |
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| Literature Cited: Beaver, B. 1999. Canine Behavior: A Guide for Veterinarians. Philadelphia: W.B. Saunders. Field, R. 1975. A perspective on syntactics of wolf vocalizations. In: The Wild Canids (Ed. by Fox, M. W.), pp. 183-201. New York: Van Nostrand Reinhold Company. Fischer, J., Cheney, D. L. & Seyfarth, R. M. 2000. Discrimination of call types by free-ranging chacma baboons (Papio cynocephalus ursinus). Folia Primatology, 71, 189-248 Sales, G., Hubrecht, R., Peyvandi, A., Milligan, S. & Shield, B. 1997. Noise in dog kennelling: Is barking a welfare problem for dogs? Applied Animal Behaviour Science, 52, 321-329. Senn, C. L. & Lewin, J. D. 1975. Barking dogs as an environmental problem. Journal of the American Veterinary Medicine Association, 166, 1065-1068. |
Excessive Barking:
As a researcher in the area of vocal communication in dogs, I've been
waiting for over a year to get my hands on this translation device. I
finally had my chance when a local television station, KTVU, sent me one to
test.
intention, even dogs that want to play can be extremely
impolite. Their poor greeting behavior or uncertainty in this excitable
situation can quickly lead to a spit and drool fight.