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Dog Speak: The Sounds of Dogs

Only recently have researchers begun to investigate whether barks produced in different contexts vary in their acoustic parameters (such as tone and pitch). Scientists theorized that if— like growls—barks displayed consistent differences, they might have a more specific communicative function, perhaps even be associated with a dog’s internal motivational or emotional state. For example, some barks might convey aggression while others might convey friendliness.

In one early study, Sophia Yin, DVM, MS, recorded a variety of breeds barking in response to different situations: a stranger ringing the doorbell (“disturbance barks”), separated from an owner (“isolation barks”) and play. Yin found that the barks did indeed have different acoustic properties. Disturbance barks were harsher and lower in pitch with little amplitude modulation, while isolation and play barks were pitched higher and had greater tonal and higher frequency and a wider range of amplitude modulation. More recent studies confirm that dog barks follow particular patterns. For example, a dog barking at a stranger sounds very different from a dog barking before going on a walk. But do these vocalizations carry meaning? They do for dogs. When dogs in one study listened to barks recorded in a new context or from a new dog, they gave more attention to the unfamiliar bark. This suggests that dogs can detect that some barks are different from others, though scientists are still exploring ways to determine how exactly they perceive and process that information. Humans, too, can decipher barks. Whether or not they’re experienced with dogs, people are quite good at classifying barks into their appropriate contexts and attributing them to perceived emotional states. After listening to randomly played recordings, people describe isolation barks as full of despair, while barks from a play session are said to be happy. Our ability to do this starts early; by age 10, children are able to assign different-sounding barks to the correct context. Today, we can distinguish the acoustic properties of certain barks so accurately that we’re able to program computers to categorize them (which confirms that computers will one day take over the earth; personally, I hope Ryan Gosling will be there to save us).

Recognizing the Patterns
How do we perceive meaning in the vocalizations of another species ? Apparently, dogs and humans have more in common than a love of shoes. Through their shared mammalian histories, canine and human vocalizations follow similar acoustic patterns. Highpitched and more tonal noises convey friendliness, affiliation and “come here,” whereas low-pitched and less tonal sounds convey aggression and “go away.” These rules and tendencies, which are found across mammalian and avian species, govern our own communication and emotional expression. When talking to infants, we generally use a highpitched “baby” tone rather than lower-register sounds.

A recent publication by Kathryn Lord, PhD, offers an additional take on why dogs bark. She and colleague Ray Coppinger, PhD, investigated the contexts in which other species use barklike sounds: “When other species emit their version of a bark, they are usually in some sort of conf licting situation. For example, an animal is at a nest or den and observes some sort of threat. Customarily, the animal would run, but because of its situation, it can’t, so it barks. We think [that] when dogs bark, they are making these sounds in association with an alert or an internal motivational state of conflict.”

In a sense, Lord and Coppinger argue that “conflicted” should be dogs’ middle name. They suggest that dogs bark in so many different situations because they often find themselves conflicted: they are in the house and want to go out, they are out and want to come in. And it may be that, through the process of domestication itself, dogs have become more prone to put themselves in these sorts of situations. In comparison with wolves, dogs have a substantially decreased f light distance; something can easily get too close before the dog feels conf licted about how to respond.

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Submitted by Mona Lindau-Webb | March 9 2013 |

Humans tend to be sooo human oriented, looking for "meaning" in animal vocalizations. Dogs bark, growl, whine, grunt, do soft mmh-mmhs, etc., etc. but the standard communication model for human speech with a speaker at one end, and a listener at the other and a "message" in between just does not fit animal communication. Animals probably do not convey information to each other. Why would they? It would not confer any survival advantage to the speaker. So instead, look at what the dog has to say from the dog's vantage point.

The frequency code as described by E.Morton has been shown to fit close communication between animals. There is now evidence from several hundred species on this, including fish and humans. The medium is the message, an animal uses ritualized communication to manipulate other animals into some sort of action. High pitch and harmonic spectrum communicate smallness, "don't hurt me", submission, friendliness, not willing to go into conflict. Low pitch and harmonic spectrum like a dog's growl is a warning. Low pitch and a spectrum with lots of noise is a dire threat that unless the listener moves away, something bad will happen.

What we call pitch is produced by the vibrating vocal cords, and animals reinforce this by also changing the resonances in the vocal tract size so that they sound smaller or larger. This is done by pulling the lips back to shorten the vocal tract so that the animal sounds smaller together with the high pitch, or by pulling the corners of the lips forward to increase the length of the vocal tract to sound larger. Look at a serious threat from a dog, the corners of the lips is the sure sign that tells you how close the dog is to follow through on the threat. In addition, dogs lower the larynx as well in a threat to sound even larger. Humans of course are totally used to decipher this, we constantly calibrate the speech of various size people to normalize the vowel space, for example.

Human speech uses the same frequency code where for example questions in many many languages are signalled by some sort of high pitch, a question meaning uncertainty, appeal to the listener. Lower or falling pitch over a sentence signals assertiveness, dominance (?), etc. So of course humans should be good at deciphering friendly and threatening canine vocalizations.

Humans also manipulate the size of the vocal tract in the same way as dogs and other animals by retracting the corners of the lips. John Ohala demonstrates that this is the answer to the eternal "riddle of the smile": why would you show all those teeth when you intend to be friendly? Well, retracting the commissure of the lips shortens the vocal tract so you sound smaller, and friendlier, and non-threatening.

Of course dogs have a lot more to say other than manipulating other beings. They certainly have the "alert alert alert" bark. There is a special high pitch of the play bark.

Some dogs use a type of harmonic spectra soft mutterings when communicating with people, never with other dogs, as if to imitate human speech to a small extent. I have observed these signals when dogs attempt to manipulate me into waking up, or getting my attention.

Canine vocalizations should really be described much more from the dogs' point of view, not from the usual anthropocentric angle. This article is quite correct that dogs have a lot to say. I also observe that dogs that have been brought up to communicate with their person
will produce fresh types of sounds that are vaguely similar to some human sounds when "talking" to their special person.

Evolution in the making???

Eugene Morton and Jake Page, Animal Talk. 1992.
John J. Ohala, The acoustic origin of the smile Journal of the Acoustical. Society of America 68.S33.1980
Mona Lindau, Testing a model of intonation in a tone language. Journal of the Acoustical Society of America. 80(3):757-64.1986

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