Understanding Dogs’ Barks

Researchers from Eotvos Lorand University in Hungary have published a new study suggesting a primitive communication system may unite virtually all mammals. The theory could help explain why previous research has shown that many mammals, including humans, understand the vocalizations of other species. In the more distant future these findings may also contribute to the development of devices for interpreting the “language” used by mammals and for interpreting human babies.

Dog barks, bird calls, and human babies’ cries may have a common functionality. It seems that basic emotions like fear, aggression, and submission are communicated in a similar acoustic way. Hungarian scientists have been studying how well people can describe the emotional content of several artificially assembled dog bark sequences.

The barks were based on sounds made by a Mudi (a Hungarian herding dog), and covered five emotional states: aggressiveness, fear, despair, playfulness, and happiness. A team of scientists led by Professor Peter Pongracz, a Professor of Ethology at the Eotvos Lorand University in Budapest, Hungary, compared the listeners’ answers and the barks’ acoustic features. They discovered that changes in three basic sound qualities, tone, pitch, and the time between barks, affected the listeners’ perception of the barks.

In general, high-pitched barks with longer intervals were rated as less aggressive than lower-pitched barks heard in frequent succession. Apparently, human babies make similar changes in sound quality when they cry. Frequency range appears to be more important than pitch when they express their needs. According to the study, the link between pitch or frequency and perceived emotion is common in many different species.

The basic argument is based on a general “physical law”: larger bodies emit sounds characterized by lower frequencies, and tend to be noisier or atonal. Therefore, it is possible to predict the size of the creature emitting the sound. The study claims that this relationship could have formed the basis of an evolutionary reutilization process, whereby low-pitched vocalizations tended to signal aggression because larger animals are more likely to win contests. In the same manner, high-pitched vocalizations became predictors of submission or friendly intent.

There are many more assumptions regarding the evolution of animal’s communication methods. Over the centuries, cats evolved ways of communicating with humans to make sure they receive the food, shelter, and affection that they want. Similarly, the researchers suspect dogs and humans share a unique ability to communicate with one another that goes beyond the proposed universal mammal ‘language’. The scientists point out that such communication isn’t limited to vocalizations, but also includes visual signals, such as changes in appearances.

Alan Beck, Professor and Director of the Center for Human-Animal Bond at Purdue University, warns that one should be careful not to interpret behavior according to “our projection of intent”. However, he admits dogs might be able to communicate with us through their barks. “As dogs and humans share some basic non-verbal communications, it is very possible that verbal ones also exist,” Beck says.

TFOT recently covered a different speech related research conducted in the UK. Researchers at the University of East Anglia (UEA) are currently developing a computerized lip-reading system, which they say may be used to fight crime. The scientists recently received a grant of over half a million dollars from England’s Engineering and Physical Sciences Research Council, and expect to complete developing the prototype within the next two years.

More information can be found on the Eotvos Lorand University website.

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